•r 


THE  LIBRARY 

OF 
THE  UNIVERSITY 

OF  CALIFORNIA 

PRESENTED  BY 

PROF.  CHARLES  A.  KOFOID  AND 
MRS.  PRUDENCE  W.  KOFOID 


SYSTEM  OF  ANATOMY 

FOR   THE  USE  OF 

STUDENTS  OF  MEDICINE. 

BY   CASPAR   WISTAR,  M.D., 

LATE  PROFESSOR  OF   ANATOMY  IN   THE  UNIVERSITY  OF   PENNSYLVANIA. 

WITH  NOTES  AND  ADDITIONS, 
BY   WILLIAM  E.   HORNER,  M.  D., 

PROFESSOR    OF    ANATOMY   IN    THE    UNIVERSITY    OF   PENNSYLVANIA. 

NINTH  EDITION, 
ENTIRELY   REMODELED, 

AND  ILLUSTRATED  BY  MORE  THAN  TWO  HUNDRED  ENGRAVINGS. 

BY   J.   PANCOAST,  M.  D., 

PROFESSOR    OF   GENERAL   DESCRIPTIVE   AND   SURGICAL   ANATOMY  IN  JEFFERSON   MEDICAL 

COLLEGE    OF    PHILADELPHIA,   LECTURER   ON   CLINICAL   SURGERY,   FELLOW 

OF   THE    PHILADELPHIA   COLLEGE   OF    PHYSICIANS,   ETC.,   ETC. 

IN  TWO  VOLUMES. 
VOL.    I. 


PHILADELPHIA: 

THOMAS,    COWPERTHWAIT   &   CO. 
1846. 


ENTERED,  according  to  the  Act  of  Congress,  in  the  year  1842,  by 

THOMAS,  COWPERTHWAIT  &  CO., 
In  the  Clerk's  Office  of  the  District  Court  of  the  Eastern  District  of  Pennsylvania. 


GREENFIELD,    MASS. 
MERRIAM   AND    MIRICK,  PRINTERS. 


ADVERTISEMENT  TO  THE  NINTH  EDITION  OF  WISTAR'S  ANATOMY. 


THE  increasing  estimation  in  which  this  favorite  Work  on  Anatomy  is  held 
by  the  Medical  Profession  of  this  country,  having  already  caused  the  last 
unusually  large  edition  to  be  exhausted,  the  publishers  in  passing  the  ninth 
edition  through  the  press,  have  been  desirous  of  rendering  it  wWthy  of  the 
continuance  of  such  gratifying  support,  by  having  such  additions  and  improve- 
ments made  as  the  progress  of  the  science  required.  With  this  object  the  text 
introduced  by  the  editor,  has  been  subject  to  revision  ;  much  new  matter  has 
also  been  added,  with  a  care  however,  not  so  to  extend  the  work  as  to  impair  its 
character  for  clearness,  brevity,  and  simplicity,  which  has  made  it  so  great  a 
favorite  with  the  Medical  Student.  Several  wood  cuts  have  been  added,  and 
the  copperplate  illustrations  of  the  Arteries  by  Sir  C.  Bell,  which  were  formerly 
sold  separate,  at  a  cost  greater  than  the  whole  of  this  work,  have  been  renewed 
by  a  skillful  engraver,  so  as  to  serve  not  only  as  an  ornament  to  the  book,  but 
an  aid  of  the  greatest  importance  to  the  Student. 

JOSEPH  PANCOAST. 
Philadelphia,  1846. 


ADVERTISEMENT  TO  THE  EIGHTH  EDITION. 


THE  publishers  of  "  Wistar's  Anatomy  for  the  use  of  Students  of  Medicine," 
gratified  with  the  favorable  reception,  which  their  attempt  to  enlarge  and  illus- 
trate this  well  known  work  has  met  with,  have  resolved  in  preparing  another 
edition  for  the  press,  to  render  it  as  far  as  is  in  their  power,  deserving  of  a  continu- 
ation of  the  patronage  it  has  received.  For  this  purpose  it  has  been  carefully  re- 
vised and  enlarged  so  as  to  include  such  important  additions  and  investigations  of 
interest  as  have  been  recently  made  in  the  science.  By  comparing  the  present 
with  the  former  editions,  the  reader  will  discover  that  these  have  been  both 
numerous  and  important  in  each  division  of  the  subject.  This  the  publishers 
have  been  enabled  to  do  without  much  increasing  the  size  of  the  volumes,  by 
substituting,  for  the  old  copperplate  prints,  a  very  large  number  of  engravings 
on  wood,  of  the  finest  description.  These  which  are  intercalated  with  the  text 
and  explained  by  foot  notes,  cannot  fail  to  render  the  work  more  convenient  and 
valuable  as  a  text-book,  in  the  various  schools  in  which  it  has  been  adopted, 
and  at  the  same  time  make  it  serve  as  a  most  useful  guide  to  the  student  in  the 
study  of  practical  anatomy.  The  additional  illustrations  have  been  taken 
mainly  from  Wilson's  Anatomist's  Vade  Mecum,  (London,  1842,)  and  partly 
from  the  English  edition  of  Cruvielhier's  Anatomy,  (London,  1842,)  and  from 
the  recent  splendid  work  on  General  Anatomy,  by  F.  Gerber.  The  present 
edition  of  Wistar,  contains  eight  colored  copperplate  engravings  of  the  blood- 
vessels, and  upwards  of  two  hundred  and  twenty  engravings  on  wood,  rendering 
it  in  this  respect  more  richly  and  amply  illustrated  than  any  other  book  of  the 
kind  that  has  yet  been  offered  to  the  American  student. 

The  same  plan  has  been  pursued  as  mentioned  in  the  preface  to  the  seventh 
edition,  of  distinguishing  the  new  matter  that  has  been  added,  from  the  original 
text  of  Dr.  Wistar. 

JOSEPH  PANCOAST. 
Philadelphia,  1842. 


DR.  HOMER'S  PREFACE. 


THE  value  of  the  present  work  having  been  sufficiently  tested  by  its  very 
diffused  use  in  the  profession,  and  by  a  third  edition  being  now  called  for,  the 
editor  has  been  induced  to  superintend  the  latter,  with  a  hope  that  its  utility  and 
the  public  conviction  in  its  favor  have  been  in  no  wise  diminished.  The  close- 
ness of  the  connexion  between  himself  and  its  lamented  author,  furnished,  also, 
another  and  a  very  powerful  reason,  why  he  should  endeavor  by  such  means 
as  he  commanded,  to  contribute  to  perpetuate  the  memory  of  a  man  whose 
literary  and  professional  career  had  been  so  conducive  to  the  reputation  of  his 
country,  and  whose  philanthropy  and  suavity  of  manners  had  established  him 
so  firmly  in  the  affections  and  confidence  of  all  who  knew  him. 

Several  amendments  have  been  introduced  by  the  way  of  corrections,  altera- 
tions and  additions.  The  latter,  for  the  most  part,  appear  between  brackets, 
and  in  the  form  of  notes,  but  there  are  many  which  could  not  be  marked  in 
such  a  manner  without  giving  the  text  a  garbled  appearance,  they  therefore 
appear  as  portions  of  the  original  work. 

The  whole  mass  of  matter  introduced  as  amendments  is  greater,  indeed,  than 
a  superficial  perusal  of  the  work  would  intimate ;  and  the  only  way  for  the 
reader  to  arrive  at  it,  will  be  by  a  careful  comparison  of  the  last  with  the  pre- 
sent edition.  The  editor,  however,  has  been  careful  not  to  allow  the  spirit  of 
change  or  improvement  to  affect  the  work  in  any  points  except  such  as  seemed 
to  him  absolutely  to  require  it,  and  where  he  was  fully  warranted  by  the  best 
authorities  in  Descriptive  Anatomy.  It  would  have  been  sufficiently  easy  for 
him  to  have  extended  the  work  considerably  beyond  its  present  dimensions  ; 
but  from  its  having  been  originally  designed  as  a  text-book  of  the  course  of 
Lectures  on  Anatomy  in  the  University  of  Pennsylvania,  and  for  the  benefit  of 
practitioners,  who  are  always  most  assisted  by  condensed  views  on  this  subject, 
he  was  apprehensive  of  perverting  or  of  frustrating  its  objects  by  such  exten- 
sion. In  consequence  of  which  he  has  principally  confined  himself  to  adding 
where  additions  were  called  for  by  recent  discoveries  in  Anatomy,  and  by  the 
omission  of  older  ones. 

Philadelphia,  Oct.  10th,  1823. 


PREFACE  TO  THE  SEVENTH  EDITION/ 


THE  publication  of  the  first  edition  of  his  "  System  of  Anatomy  for  the  use 
of  Medical  Students/'  was  completed  by  Dr.  Caspar  Wistar  in  1814.  Simple 
in  its  construction,  concise,  but  yet  clear,  and  at  the  same  time  representing 
faithfully  and  fully,  the  science  of  Anatomy  as  it  then  existed,  the  book  was 
exactly  in  keeping  with  the  well  known  character  of  its  distinguished  author. 
The  general  approval  with  which  it  was  received  in  this  country,  was  manifest- 
ed by  the  rapidity  of  its  sale. 

The  second  edition  which  was  called  for  in  1817,  was  further  improved  by 
the  author,  by  the  addition  of  such  new  anatomical  facts  as  had  come  to  his 
knowledge,  and  such  further  physiological  observations  as  served  to  give  life 
and  interest,  to  the  otherwise  dry  details  of  his  science.  In  1818.  before  his 
work  had  reached  the  third  edition,  the  author  himself  died,  regretted  by  all 
who  loved  virtue,  honored  science,  or  knew  how  to  estimate  a  kindness  of  soul, 
and  uniform  urbanity  of  manner,  which  is  yet  vivid  in  the  recollection  of  his 
friends. 

The  superintendence  of  the  third  edition  was  assumed  by  Professor  Homer, 
a  personal  friend  of  Dr.  Wistar,  who  enriched  it,  by  the  addition  of  much  valu* 
able  matter,  which  the  science  in  its  onward  progress  had  at  that  time  develop- 
ed. The  value  of  these  additions,  may  be  inferred,  from  the  increasing  favor 
which  the  medical  public  has  continued  to  extend  towards  the  work;  four 
editions  having  been  completely  exhausted  since  that  period. 

Though  fifteen  years  only  have  elapsed,  since  its  former  revision,  the  zealous 
and  persevering  inquiries  of  modern  anatomists,  which  have  scarcely  their  par- 
allel in  any  other  department,  have  in  that  time  added  much  to  the  science. 
The  present  publishers  have  therefore  been  desirous,  that  the  work  should  be  so 
extended  and  remodeled,  as  to  be  brought  up  as  near  as  may  be,  to  the  existing 
state  of  the  science,  without  impairing  its  value  as  a  manual  by  too  much  in- 
creasing its  bulk.  The  reader  will  discover  how  far  the  attempt  has  been  suc- 
cessful, by  comparing  this  with  former  editions. 

Within  the  period  alluded  to,  the  department  of  general,  more  than  that  of 
special  anatomy,  has  yielded  the  richest  harvest  to  the  anatomist,  and  has  been 
advantageously  cultivated  with  particular  reference  to  physiology  and  thera- 
peutics. From  general,  then,  more  than  from  special  anatomy,  have  the  pre- 
sent additions  been  derived;  the  editor  believing  that  in  mere  special  descrip- 
tion, that  which  is  most  concise  and  yet  so  comprehensive  as  not  to  omit  any 
I* 


VI  PREFACE. 

thing  of  real  importance,  is  the  best.  He  has  not,  therefore,  added  a  great  deal 
to  the  individual  description  of  the  bones,  ligaments,  muscles,  blood-vessels, 
and  nerves.  But  in  the  department  of  General  Anatomy,  and  especially  in 
Splanchnology — the  viscera  being  so  important  in  a  medical  point  of  view — 
the  student  will  find  the  additions  to  have  been  both  numerous  and  extensive. 

The  department  of  Neurology,  which  has  been  the  fashionable  anatomical 
study,  for  years  past,  and  upon  which  hangs  so  much  that  is  important  in 
physiology  and  medicine,  has  appeared  to  him  more  deficient  than  any  other 
portion  of  the  original  work,  as  the  brain  and  spinal  marrow  have  been  describ- 
ed by  Dr.  Wistar,  only  from  above  downwards ;  a  method  which  was,  however, 
the  most  approved  and  general  in  his  day.  The  editor  has  therefore  added  two 
entire  chapters  on  that  subject,  one  on  the  General  Anatomy  of  the  Nervous 
vSystem,  and  one  on  the  special  description  of  the  Spinal  Marrow  and  Brain 
from  below  upwards,  in  the  order  of  its  development  and  the  direction  of  its 
functions,  retaining,  nevertheless,  here  as  in  other  parts,  all  the  original  text. 
It  has  also  been  thought  advisable,  to  transpose  several  portions  of  the  work, 
when  by  so  doing,  parts  belonging  to  the  same  general  tissue  could  be  placed 
in  more  natural  connexion,  and  made  to  correspond  with  the  mode  in  which 
they  are  usually  described. 

Thus,  the  account  of  the  brain,  the  eye  and  the  ear,  has  been  transferred  from 
the  first  volume  to  the  second,  and  placed  in  continuity  with  that  of  the  other  parts 
of  the  general  nervous  system.  To  facilitate  the  student  in  the  aquisition  of 
this  difficult  science,  all  the  plates  of  the  former  edition,  which  were  sufficiently 
accurate  to  be  useful,  have  been  retained,  and  several  other  copperplate  engrav- 
ings of  the  blood-vessels  added,  with  upwards  of  a  hundred  wood  cuts,  some 
of  which  are  original,  but  the  greater  part  collected  with  considerable  care  and 
labor  from  the  newest  and  most  approved  sources. 

The  amount  of  the  new  matter  added  to  this  edition  is  nearly  equal  to  a 
fourth  part  of  the  whole.  The  student,  will,  however,  be  enabled  to  distinguish 
readily  the  original  text  of  Dr.  Wistar,  from  the  additions  which  have  been 
made  either  by  Dr.  Horner,  which  are  all  included  in  brackets  [],  or  from  those 
of  the  present  editor,  which  are  separated  from  the  other  parts  of  the  work  by 
their  commencing  and  terminating  with  a  dash  — .  Various  synonyms  introduc- 
ed throughout  the  work,  and  some  more  trifling  emendations  of  the  text,  it  has 
not  been  thought  necessary  to  designate. 

JOSEPH  PANCOAST. 

Philadelphia,  Dec.  1,  1838. 


CONTENTS  OF  VOL.  I. 


PART  I. 

OSTEOLOGY. 
CHAPTER  I. 

GENERAL   ANATOMY    OF    THE    OSSEOUS    SYSTEM. 

CLASSIFICATION  and  Structure  of  Bones,       -            -            -  -        13 

Of  the  Periosteum,                                                 -            -            -  33 

Medullary  Membrane  or  Internal  Periosteum,  -        33 

Cartilages  and  their  Structure,      -  36 

Accidental  development  of  Cartilages,                                      -  -        39 

Of  the  Formation  of  Bone,  40 

Formation  of  Callus,  -  -48 

Terms  used  in  the  Description  of  Bones  and  Joints,  51 

CHAPTER  II. 

OF    THE   SKELETON    AND    ITS    DIFFERENT   PARTS. 

Of  the  Head,                                                     -            -            .  -        54 

Sutures,    -  57 

Os  Frontis,      -  61 

Ossa  Parietalia,     -                                                  -  64 

Ossa  Temporum,  66 

Qs  Occipitis,                                                ...  73 

Os  Ethmoides,                                                   -            -  -        75 

Os  Sphenoides,     -                                     -            -            -  80 
Foramina  of  the  Sphenoidal  Bone,    -                         ...        84 

Of  the  Face,         -                                                  ...  85 

Ossa  Maxillaria  Superiora,      -                                     -  -        86 

Ossa  Nasi,                                                   ...  89 

Ossa  Lacrymalia  seu  Unguis,                            -            -  -        90 

Ossa  Malarum,      -                                     -            -            -  91 
Ossa  Palati,     -                                     ....        93 

Ossa  Spongiosa,  or  Turbinata  Inferiora,   -            -            -  95 


Vill  CONTENTS. 

OftheVomer,  -        95 

Maxilla  Inferior,  -  96 

Teeth,  -        99 

Composition  of  the  Teeth,  100 

Development  of  the  Teeth,    -  -      1 10 

Of  the  Enamel,    -  112 

Permanent  Teeth,       -  -      113 

Aberrations  of  Dentition,  -                         117 

OsHyoides,   *•  -      118 

Regions  of  the  Skull,  '    -                                                   119 

Orbit  of  the  Eye,        -  -      120 

Cavities  of  the  Nose,  -                                                               122 
Cavity  of  the  Cranium  and  Internal  Basis  of  the  Skull,         -      125 

External  Basis  of  the  Skull,        -  128 

Side  of  the  Head,       -  -      131 

Form  of  the  Cranium,  -                                                                  132 

Head  of  the  Foetus,    -  -      135 

Trunk,      -  137 

Spine,  ...      137 

True  Vertebra,     -  138 

False  Vertebra?,  -      151 

Vertebral  Cavity  for  containing  the  Spinal  Marrow,  154 

Thorax,  (  -      155 

Ribs,  155 

Sternum,         -  -      160 

Movement  of  the  Ribs  and  Sternum  in  Respiration,  163 

Pelvis,  -      163 

Os  Ilium,  -  164 

Os  Ischium,     -  -      166 

Os  Pubis,  -  167 

Trunk  of  the  Foetus,  -  -      173 

Superior  Extremities,  -                                                               174 

Clavicle,  -      175 

Scapula,    -  177 

OsHumeri,     -  -      181 

Forearm,  -  185 

Ulna,  -  -      186 

Radius,    -  188 

Hand,  -      190 

Carpus,     -  191 

Metacarpus,    -            -  -            -            -            -            -196 

Thumb  and  Fingers,  199 

Inferior  Extremities,  -  -                              201 


CONTENTS.  ]X 

Of  the  Thigh,      -  -            201 

Tibia,              -                                     -  -      205 

Fibula,      --•„--  -            207 

Patella,  -      209 

Foot,         -       .    -  211 

Tarsus,                                                              -            -  -      211 

Metatarsus,  217 

Toes,  -      219 

General  Structure  of  the  Foot,     -  219 


PART  II. 
SYNDESMOLOGY. 

CHAPTER  III. 

GENERAL  ANATOMY  OF  THE  LIGAMENTOUS,  FIBROUS,  OR  DESMOID  TISSUE.  223 

Ligaments  of  the  Joints,        -  -      226 

Of  the  Yellow  Elastic  Ligamentous  Tissue,        -  229 

Fibro  Cartilaginous  Tissue,   -  -      230 

CHAPTER  IV. 

A  GENERAL  ACCOUNT  OF  ARTICULATIONS,  AND  OF  BURS.E  MUCOS^.   232 

CHAPTER  V. 

OF  PARTICULAR  ARTICULATIONS. 

The  Connexion  of  the  Head  with  the  Vertebrae,        -  -      239 

Articulations  of  the  Vertebrae  with  each  other,  --                       241 

Articulation  of  the  Lower  Jaw,         -  -      244 

Articulations  of  the  Clavicle  and  Scapula,  245 

Articulation  of  the  Os  Humeri  and  Scapula,  -      246 

.  Elbow,  248 

Wrist,      -  -      250 

Carpal  and  Metacarpal  Bones,  -                         254 

Fingers,  -  -      255 

Ribs,  -  255 

The  Hip  Joint,  -      257 

Articulation  of  the  Knee,  -                         259 

Tibia  and  Fibula,  -      263 

Leg,  Foot,  and  Ankle  Joint,  264 

Tarsus  and  Metatarsus,  -            -  -            -      266 


CONTENTS. 


CHAPTER  VI. 

OF   PARTICULAR    LIGAMENTS   AND    THE    SITUATION   OF   THE    INDIVIDUAL 

BURS-E    MUCOS.&. 

Ligaments  proper  to  the  Scapula,      -  -      268 

Interosseous  Ligament  of  the  Forearm,  -            -  268 

Ligaments  retaining  the  Tendons  of  the  Head  and  Fingers  in  their 

position,  -      269 

Ligaments  on  the  Anterior  part  of  ike  Thorax,  -  270 

of  the  Pelvis,       -  -      270 

retaining  the  Tendons  of  the  Foot,    -  274 

Enumeration  of  the  most  important  Bursas,  -      275 


PART  III. 

MYOLOGY. 

CHAPTER  VII. 

GENERAL    ANATOMY    OF    THE    MUSCLES.  279 

Of  the  Tendons,  and  of  Muscular  Motion,     -  -     287 
CHAPTER  VIII. 

OF    THE    INDIVIDUAL    MUSCLES.  300 

Muscles  of  the  Teguments  of  the  Cranium,  -      300 

Ear,  301 

Eyelids,  -      302 

Eyeball,  303 

Nose,  -  -      306 

Mouth  and  Lips,  -  306 

Lower  Jaw,    -  -      311 

Anterior  part  of  the  Neck,  313 

between  the  Lower  Jaw  and  the  Os  Hyoides,  -      314 

Os  Hyoides  and  the  Trunk,  316 

situated  about  the  Fauces,    -  -      319 

on  the  Anterior  part  of  the  Neck  close  to  the  Vertebrae,  321 

on  the  Anterior  part  of  the  Thorax,  -      323 

between  the  Ribs,                                       .  _            .             334 

on  the  Abdomen,       -            -                         -  -            _      335 

about  the  Male  Organs  of  Generation,    -  335 

of  the  Anus,  ----.„.      339 


CONTENTS.  XI 

Muscles  of  the  Female  Organs  of  Generation,  -                                      341 

within  the  Cavity  of  the  Abdomen,  -      342 

on  the  Posterior  part  of  the  Trunk,  -                                       348 

of  the  Superior  Extremities,  -      359 

Inferior  Extremities,       -  -            -^/        375 

CHAPTER  IX. 

OBSERVATIONS    ON    THE    MOTIONS    OF  THE   SKELETON.                   397 


PART  IV. 

OF  THE  GENERAL  INTEGUMENTS,  OR  OF  THE 

CELLULAR  MEMBRANE  AND  THE  SKIN.  - 

CHAPTER  X. 

OP    THE   CELLULAR    MEMBRANE.  403 

CHAPTER  XL 

Of  the  Cutis  Vera,  411 

Rete  Mucosum,  -     415 

Derma,      -  425 

Papillary  Body,  or  Neurothelic  Apparatus,     -  -      425 

Sudoriferous  Apparatus,  -                                                  -  426 
Inhaling  Apparatus,    ------      427 

Blennogenous  Apparatus,              ...  428 

Chromatogenous  Apparatus,               -  -      429 

Cuticle,  or  Epidermis,       -  430 

Nails,  -      439 

Hairs,       -------  441 


PART  V. 

OF  THE  NOSE,  THE  MOUTH,  AND  THE  THROAT. 
CHAPTER  XII. 

OF   THE   EXTERNAL   NOSE.  446 

Of  the  Cavities  of  the  Nose,  -      449 

CHAPTER  XIII. 

I 

OF    THE    MOUTH.  458 

Of  the  Tongue,          -  -  -  -  -  -  -      462 

The  Salivary  Glands,      -  -  -  -  -  -  469 


Xll 


•  CONTENTS. 

CHAPTER  XIV. 

OF    THE    THROAT. THE    ISTHMUS    AND    FAUCES. 


Of  the  Larynx, 

Muscles  of  the  Larynx,    - 
Thyroid  Gland, 
Pharynx,  - 


474 

476 

483 
487 
490 


FAifr  vi. 


OF    THE    THORAX. 

THE   MAMMAE.  493 

CHAPTER  XV. 

OF    THE    GENERAL   CAVITY    OF   THE    THORAX.  497 

CHAPTER  XVI. 

OF  THE  HEART  AND  PERICARDIUM,  AND  THE  GREAT  VESSELS. 

Of  the  Pericardium,  -  -  502 

Heart,       -  504 
Aorta,  Pulmonary  Artery  and  Veins,  and  the  Venae  Cavse  at 

their  commencement,       -  -  514 

CHAPTER  XVII. 

OF  THE  TRACHEA  AND  THE  LUNGS. 

Of  the  Trachea,  -  517 

Lungs,  -  -  -  520 

Thorax  of  the  Foetus,  -  526 

Thymus  Gland,  -  526 

Heart,  -  529 

Pulmonary  Artery  end  the  Aorta,  531 

Lungs  of  theTcetus,  -  532 

Cases  of  Malformation,   -  533 


, 


- 


SYSTEM  OF  ANATOM>Y. 


PART   I. 

OSTEOLOGY. 

CHAPTER  I. 

GENERAL  ANATOMY  OF  THE   OSSEOUS    SYSTEM. 

Classification  and  structure  of  bones— Chemical  composition — Recent  researches 
on  the  intimate  structure  of  bone — Periosteum — Medullary  membrane — Car- 
tilages— Formation  of  bone — Terms  used  in  describing  bones. 

— THE  osseous  tissue  in  man  and  nearly  all  large  animals 
not  inhabiting  a  dense  medium,  constitutes  that  scaffolding 
or  framework,  upon  which  is  supported  all  the  soft  parts  of 
the  body.  Hence  the  bones  when  seen  in  connexion  in  a 
perfect  skeleton,  present  so  perfect  an  outline  of  the  animal  to 
which  they  belonged,  as  to  be  sufficient  as  has  been  shown  by 
Baron  Cuvier,  to  indicate  clearly  its  shape,  size,  and  mode  of 
life  as  well  as  the  nature  of  the  food  upon  which  it  lived.* 
— The  bones  may  be  considered*  as  designed  for  the  fulfilment 
of  two  principal  objects — the  formation  of  cavities  for  the 
protection  of  delicate  and  important  organs,  as  in  the  head, 
thorax,  and  pelvis — and  of  columns  and  levers  for  support  and 

*  A  skeleton,  or  a  structure. analogous  to  it  in  its  uses,  that  of  forjpng  a 
foundation  upon  which  the  body  can  be  built,  and  to  which  the  muscles  may  be 
attached  in  order  to  move  it  from  place  to  place,  is  found  in  the  mammiferae, 
birds,  and  many  fishes,  in  the  interior  of  the  body ;  in  the  Crustacea  and  teslacea, 
some  fish,  reptiles,  &c.,  it  is  wholly  or  in  part  at  the  exterior.  In  a  great 
majority  of  cases  it  is  bony  in  its  structure  ;  it  is,  however,  cartilaginous  in 
many  fishes,  and  fibrous  in  nearly  all  coleopterous  insects,  of  which  it  forms 
the  external  covering.— p. 


14  CLASSIFICATION    OF    THE    BONES. 

motion,  as  in  the  spinal  column  and  the  upper  and  lower  ex- 
tremities. They  perform,  however,  but  a  passive  or  mechanical 
part  in  the  movements  of  the  body,  forming  supporting  organs, 
round  which  the  muscles,  nerves  and  vessels  are  wreathed,  and 
at  the  same  time  serve  as  levers,  by  which  the  limbs  are  lifted. 
They  are  necessarily  very  numerous  in  the  human  body,  and 
exist  as  separate  and  distinct  pieces,  which  touch  one  another 
at  their  extremities,  where  they  are  generally  expanded  in. size, 
and  their  parts  so  nicely  adjusted  to  each  other,  as  to  form 
the  basis  of  the  structure  of  the  joints.  At  these  places  of 
junction,  the  bones  are  fastened  together,  by  strong,  fibrous, 
inelastic,  inextensible  bands,  called  ligaments. 
— The  number  of  the  bones  in  the  human  body,  varies  accord- 
ingly as  we  examine  them,  in  infancy,  middle  life,  or  in  old 
age.  Nearly  all  the  individual  bones  of  the  adult,  are  developed 
in  separate  pieces  in  the  infant,  the  number  of  which  is  very 
great,  and  their  consolidation  into  single  bones,  is  not  general 
and  complete  till  about  the  period  of  puberty :  many  of  these 
separate  bones  of  the  adult,  especially  of  the  head  and  trunk, 
are  found  fused  together  in  extreme  old  age. 
— Anatomists  have  generally  agreed  to  consider  as  distinct 
bones,  those  of  the  adult,  and  to  these  they  have  given  indi- 
vidual names.  The  skeleton  is  divided  into  trunk,  head,  and 
extremities  : 

—Thus  there  are  for  the  trunk,  fifty-three   bones  ;  the  twenty-  , 
four  true  vertebras,  the  sacrum,  the  coccyx,  twelve  ribs  on  each 
side,  one  sternum  in  three  pieces,  and  two  ossa  innominata. 
— For   the   head,   fifty-nine    bones ;    the   occipital,    sphenoid, 
ethmoid,  frontal,  the   two   parietal,  two   temporal  with   the  four 
small  bones  of  the   ear,  the  vomer,  the  two  superior  maxillary, 
two  palatine,  two  molar,  two  nasal,  two  lachrymal  or  unguiform, 
iwo  inferior  turbinated,  the  inferior  maxillary,  the  teeth,  and   the 
hyoid  bone. 

— For  the  two  upper  extremities,  seventy-four  bones  ;  there  are 
on  each  side,  the  scapula,  clavicle,  humerus,  radius,  ulna,  eight 
wrist  or  carpal  bones,  five  metacarpal,  fourteen  phalanges,  and 

five  sesamoid  bones. 

-  ? 


CLASSIFICATION    OF    THE    BONES.  15 

— For  the  two  lower  extremities,  sixty-six  bones  ;  on  each  side 
one  femur,  a  tibia,  a  fibula,  patella,  seven  ankle  or  tarsal  bones, 
five  metatarsal,  fourteen  phalanges  of  the  toes,  and  two  and  some- 
times three  sesamoid.  Thus  according  to  the  enumeration  of 
Marjolin,  there  are  two  hundred  and  fifty-two  bones  in  the  human 
body.  The  number  of  sesamoid  bones,  however,  is  very  varia- 
ble ;  and  some  anatomists  of  high  reputation,  do  not  include  the 
teeth  in  the  enumeration  of  the  bones  of  the  body. 
— The  bones  are  all  either  symmetrical  or  unsymmetrical. 
The  symmetrical  bones  are  in  pairs,  and  correspond  in  size 
and  shape  very  nearly  with  each  other,  and  are  placed  upon 
either  side,  like  those  of  the  extremities  and  ribs.  The  unsym- 
metrical, which  consist  of  some  of  the  bones  of  the  head,  the 
sternum,  vertebrae,  sacrum,  os  coccygis  and  os  hyoides,  are 
situated  in  the  middle  line  of  the  body.  The  lateral  halves  of 
these  bones  correspond  very  closely  with  each  other. 
— From  their  general  form  and  geometrical  dimensions,  the 
bones  have  been  divided  into  classes  ;  the  long  bones,  ossa 
longa,  the  broad  bones,  ossa  lati,  and  the  thick  bones,  OSSQ, 
crassa.  The  long  bones,  occupy  the  centre  of  the  limbs,  are 
the  levers  used  in  locomotion,  and  form  a  series  of  "broken 
columns,  articulated  together,  which  increase  in  number,  and 
diminish  in  si^e,  as  they  recede  from  the  trunk.  They  are 
divided  into  a  middle  part,  body  or  diaphysis  ;  and  into  extre- 
mities or  epjphyses.  The  body  is  cylindrical  in  some,  prismatic 
and  triangular  in  others,  and  generally  a  little  curved  or  twisted. 
The  extremities  are  expanded  and  thick.  The  bodies  which 
are  the  smallest  part,  happily  correspond  with  the  bellies  or 
largest  .part  of  the  muscles — the  extremities  with  their  narrow 
tendinous  terminations. 

— The  broad  bones  assist  in  forming  a  part  of  the  walls  of  the 
trunk  and  head  ;  they  are  flattened,  more  or  less  concave  on 
their  interior,  varied  in  their  form,  and  thicker  usually  at  their 
margins,  than  at  their  centres. 

— The  thick  bones  are  assembled  in  masses,  and  form  parts  at 
once  solid  and  moveable  as  in  the  spinal  column,  the  wrist,  and 
the  ankle. 


16  STRUCTURE    OF    THE    BONES. 


-«- 


— The  human  bones  in  a  recent  adult  subject,  are  of  a  dull 
white  color :  they  possess  considerable  elasticity,  but  little 
flexibility,  have  the  greatest  specific  gravity  of  any  portion  of 
the  human  body,  and  (are  liable  to  be  broken  by  accidents  or 
even  by  violent  muscular  efforts.  Their  texture  is  varied  not 
only  in  different  parts  of  the  skeleton,  but  in  different  parts^of 
the  same  bones.  Thus  in  the  long  bones,  the  middle  portion 
or  diaphysis  is  compact,  or  nearly  solid,  with  a  cavity  in  the 
centre ;  the  extremities  are  cellular  or  spongy,  with  but  a  thin 
coating  of  the  compact  matter;  and  the  central  cavity,  is  occu- 
pied by  a  long  network  formed  of  thin  plates  and  fibres,  called 
the  reticulated  tissue  of  the  bones. 

— In  flat  bones  the  external  surfaces  are  composed  of  firm 
plates  of  compact  bone  ;  but  the  internal  substance  is  cellular. 
In  some  of  these  bones,  the  cellular  tissue  exists  in  such  small 
quantity,  that  the  external  compact  layers  almost  touch,  and  the 
bones  become  then  diaphanous  or  translucent. 
— The  thick  bones  are  formed  almost  entirely  of  the  spongy  or 
cellular  substance,  which  is  surrounded  by  an  extremely  thin 
shell  of  the  compact  bony  matter,  and  are  somewRat  darker  in 
color  than  the  long  or  the  flat. 

—The  osseous  tissue  thus  presents  three  modifications  of  form  : 
the  compact,  the  reticular,  and  tho  cellular  ui  spungy.  The 
compact,  which  is  the  densest  and  strongest,  is  placed  upon  the 
outer  surface  of  all  the  bones  of  the  body  ;  it  forms  a  covering 
of  greater  or  less  thickness  to  all  the  flat  and  thick  bones,  and 
adds  to  their  strength,  without  much  increasing  their  weight. 
The  long  bones,  which  are  narrowed  down  in  the  shaft,  so  as 
to  accommodate  the  muscles  without  destroying  the  symmetry 
of  the  limbs,  and  require  to  be  made  of  the  strongest  material, 
have  their  shafts  or  bodies  formed  almost  entirely  of  the  com- 
pact portion.  The  cellular  or  spongy  is  found,  in  a  greater  or 
less  degree,  in  every  bone  of  the  body  ;  in  the  extremities  of 
the  long  bones  it  is  continuous,  though  indirectly,  with  the 
reticulated  tissue  of  the  central  or  medullary  canal.  The 
reticulated  tissue  has  been  considered  only  a  modification  of  the 
spongy,  being  formed  of  larger  cells  with  a  more  open  and 
delicate  texture. 


STRUCTURE     Q$    THE    BONES,  17 

[The  cellular  structure  of  bones  is  attended  with  several 
important  advantages.  In  the  cylindrical  bones  it  gives  great 
additional  strength,  by  increasing  their  diameter,  without  adding 
to  their  weight ;  for  by  swelling  out  their  articular  e/tfemities, 
it  produces  much  greater  security  of  the  joints,  by  obviating  the 
tendency  to  dislocation,  and  rendering  their  movements  more 
steady.  A  simple  experiment  will  satisfy  any  one  that  the 
increase  of  volume  in  the  extremities  of  the  long  bones,  is  not 
attended  with  an  increase  of  osseous  matter;  for  in  the  dried 
bone,  the  section  of  an  inch  from  the  centre  gill  weigh  as  much 
as  the  same  length  from  the  extremities,  notwithstanding  the 
greater  size  of  the  latter.  *Dr.  Physick  has  pointed  out  another 
very  important  advantage  of  the  cellular  structure  of  bones, 
besides  those  of  its  making  them  nearly  as  strong  as  if  they 
were  solid,  and  at  the  same  time  diminishing  what  otherwise 
would  have  been  a  weight  too  oppressive  for  the  muscular 
powers.  He  thinks  that  thereby  the  concussion  of  the  brain, 
and  of  the  other  viscera  is  frequently  prevented  ;  and  in  nearly 
all  cases  diminished,  in  falls  and  in  blows.  He  illustrates  the 
position  by  showing,  first,  the  concussion  which  takes  place 
through  a  series  of  ivory  balls  suspended  by  threads ;  if  one  be 
drawn  to  some  distance  from  the  others,  and  allowed  to  impel 
them  by  falling.  The  momentum  in  this  case  impels  the  ball  at 
the  farther  end  of  the  row,  almost  to  the  distance  from  which 
the  first  one  fell.  But  if  a  ball  of  the  same  size,  composed  of 
the  cellular  structure  of  bone,  be  substituted  for  one  of  the  ivory 
balls,  and  the  experiment  be  repeated,  the  momentum  of  the 
first  ball  is  lost  almost  entirely  in  the  cellular  structure  of  the 
substitute ;  particularly  if  the  latter  be  well  soaked  previously  in 
water,  so  as  to  give  it  a  condition  in  point  of  moisture  allied  to 
the  living  state.  Adopting  this  experiment  as  demonstrative  of 
the  fact,  Dr.  Physick  asserts,  that  in  falls  from  an  eminence 
upon  the  feet,  the  percussion,  by  the  time  it  has  passed  through 
the  cellular  structure  of  the  foot,  leg,  thigh,  vertebral  column 
and  the  condyles  of  the  occiput,  is  very  much  diminished  in 
force,  and  carries  much  less  impulse  upon  the  brain.  /  Again,  in 
2* 


18  STRUCTURE    OF    THE    BONES. 

blows  on  the  head,  the  brain,  though  much  protected  from 
external  injury  by  the  arched  form  of  the  cranium,  has  an 
additional  security  -from  the  interposition  of  the  diploe,  wKich 
weakens  the  force  of  the  blow. 

In  all  the  bones  there  are  canals,  independent  of  the  cellular 
structure,  which  penetrate  to  a  greater  or  less  extent  between 
the  lamina,  and  go  in  various  directions,  some  longitudinal, 
others  oblique  and  transverse.  These  canals  transmit  the  blood- 
vessels, and  were  first  pointed  out  with  exactitude  by  Clopton 
Havers,  an  English  anatomist.  But  he  assigned  a  wrong 
application  to  them,  as  he  believed  that  the  marrow  ran  through 
them,  in  order  to  make  the  bones  supple,  and  to  unite  their 
lamina  more  strongly.  S.  B.  Albinus  corrected  the  mistake,  by 
demonstrating  that  they  were  filled  with  blood-vessels.  These 
canals  in  a  vertebra  are  particularly  large,  and  open  on  the 
posterior  face  of  its  body,  by  one  or  two  large  foramina.  In 
the  cranium  they  are  remarkably  well  seen  ;  but  their  discovery 
is  of  more  modern  date.  M.  Portal  says,  that  in  the  bones 
each  kind  of  vessel  has  a  particular  canal  for  itself  alone ;  those 
of  the  arteries  are  therefore  to  be  readily  distinguished  from 
such  as  belong  to  the  veins  and  to  the  nerves ;  and  this  takes 
place  both  in  the  large  and  in  the  small  canals.  Occasionally 
the  vessels  dip  into  a  common  canal,  but  if  any  one  will  take 
the  trouble  to  follow  them,  he  will  find  them  ultimately 
separating  from  each  other.] 

— The  canals  for  the  transmission  of  blood-vessels,  which 
exist  in  abundance  in  the  compact  bony  tissue,  cannot  be  well 
seen  in  the  healthy  state,  except  by  the  aid  of  the  microscope. 
With  the  aid  of  this  instrument  they  may  be  seen  in  great 
numbers,  running  in  a  longitudinal  direction,  opening  in  its 
internal  or  medullary  cavity,  so  as  to  maintain  a  free  commu- 
nication between  the  vessels  on  the  exterior,  and  those  in  the 
cavity  of  the  bone. 

— When  cut  in  surgical  operations,  blood  issues  from  the 
compact  substance,  which  is  also  susceptible  of  inflammation 
and  its  consequences  like  other  vascular  parts.  In  inflammation, 


STRUCTURE    OF    THE    BONES.  19 

the  compact  portion,  is  sometimes  seen  swelled  and  expanded, 
so  as  to  develop  in  its  substance,  a  cellular  arrangement, 
somewhat  like  that  of  the  co'mmon  spongy  tissue.  Maceration 
of  a  bone  in  water,  after  its  earthy  part  has  been  removed, 
exhibits  the  same  cellular  structure.  In  fact,  the  principal 
difference  between  these  varieties  of  bony  tissue,  consists  in 
their  difference  of  density,  with  some  variation  in  the  disposition 
of  their  fibres  ;  the  cells  being  condensed  in  the  compact  portion 
so  as  to  admit  of  a  decrease  in  the  diameter  of  the  bones, 
without  a  corresponding  diminution  of  their  strength.  Hence 
the  amount  of  substance  being  the  same,  in  the  extremities  and 
shafts  of  the  long  bones,  sections  of  equal  length  must  of  course 
be  of  equal  weight. — 

— In  structure  bone  is  composed  of  lamellae,  which  are  con- 
centric in  long  and  parallel  in  flat  bones.  Between  the  lamellae 
run  the  vascular  canals  of  the  bones,  and  are  lodged  the  bony 
corpuscles,  which  have  been  lately  discovered.  See  p.  46. 
— In  the  firmness  of  their  texture  and  their  general  aspect, 
bones  resemble  inorganic  matter,  but  they  are  nevertheless 
highly  organized.  /c02 

For  example,  if  a  bone  be  macerated  in  certain  acid  liquors,  J 
the    earthy  matter   will    be    dissolved,  and    a    membranous   orj        fj/% 
cartilaginous   substance   will    remain,   resembling   the    bone    inl 
form  and  size.* 

If  the  bones  of  a  young  subject,  after  being  injected,  be  treated 
in  the  same  way,  this  membranous  substance  will  appear  to  be 
very  vascular — when  the  injection  has  been  successful,  it  will 
appear  uniformly  reddened  by  the  greatest  number  of  vessels 
which  are  filled  with  the  matter  of  injection.  These  vessels 
discharge  blood  when  the  periosteum  is  removed  from  the 
surface  of  bones,  in  the  living  subject,  and  they  also  form 
granulations  upon  bony  surfaces  that  have  been  thus  denuded. 

— On  the  other  hand  if  a  recent  bone  be  exposed  for  a 
considerable  time  to  the  action  of  a  moderate  fire,  or  boiled  for 

*  One  part  of  muriatic  acid  to  thirty  of  water  is  a  good  mixture  for  this 
purpose,  by  taking  care  to  keep  up  the  strength  of  the  mixture  by  additions  of 
the  acid  from  time  to  time. — H. 


20  STRUCTURE    OF    THE    BONES. 

a  long  period  in  a  Papin's  digester,  the  other  element  of  the 
bone  may  be  obtained — its  earthy  structure — in  a  separate 
state,  representing  the  original  perfectly,  in  size  and  shape.  It 
is  then  perfectly  white,  and  is  so  light  and  brittle  as  to  crumble 
on  the  slightest  touch. 

— Exposure  of  bones  for  a  long  time  to  the  action  of  the  climate, 
will  cause  it  to  shell  off  in  layers  and  fall  into  powder,  from  the 
same  cause,  the  destruction  of  its  animal  matter. 
— A  bone  macerated  in  acid,  or  well  incinerated,  may  be  torn 
or  split  in  particular  directions,  more  readily  than  others,  and 
manifests  an  apparent  fibrous  arrangement. 

*"" — In  regard  to  the  disposition  and  arrangement  of  these  fibres, 
anatomists  differ,  though  it  has  been  with  them  a  subject  of 
much  research.  The  length  of  each  fibre  is  limited,  running 
but  a  small  part  of  the  length  of  the  long  bones,  but  is  much 
greater  than  its  breadth  and  thickness.  The  greater  part  arc- 
longitudinal,  that  is,  run  in  the  direction  of  the  axis  of  the 
bone ;  some  are  transverse  and  some  oblique.  From  the 
shortness  and  varied  direction  of  the  fibres,  and  the  cellular 
appearance  of  the  bone  when  macerated,  Scarpa  denied 
entirely,  the  existence  of  a  fibrous  arrangement  in  the  bones, 
and  considers  them  composed  throughout,  exclusively  of 
cellular  substance,  more  or  less  compacted. 
— Malpighi  and  Havers,  believed  the  bones  made  up  wholly  of 
concentric  lamellae,  -formed  of  fibres  and  filaments,  encrusted 
with  osseous  matter,  laying  over  each  other  like  the  leaves  of 
a  book.  Gagliardi  believed  also,  that  these  lamellae  were  united 
together  by  little  pins  of  the  same  material :  some  of  which 
were  straight,  some  oblique,  and  some  he  fancied  had  round 
heads.  De  Lasone  says  that  these  lamellae  are  made  up  of  ossi- 
fied fibres,  united  by  oblique  ones,  and  Reich  el,  that  the  lamellae 
and  fibres,  form  a  porous  tubulated  tissue,  continuous  with 
the  spongy  substance.*  According  to  J.  F.  Meckel,  the  proper 

*  The  opinions  of  these  different  anatomists  are  interesting  mainly  as  con- 
nected with  the  history  of  the  science.  The  discrepancies  existing  between  them, 
may  now  readily  be  reconciled,  since  the  true  composition  or  structure  of  bone 
has  been  rendered  apparent  by  the  use  of  the  microscope.  See  page  46.— p. 


STRUCTURE    OF    THE    BONES.  21 

substance  of  the  bones,  is  of  a  fibro-laminated  nature,  the 
fibres  in  some  parts  being  so  closely  aggregated,  as  to  form  a 
compact  bone,  and  separated  and  expanded  in  others,  so  as  to 
constitute  the  cells  of  the  spongy  portion.  The  longitudinal 
fibres  are  much  the  most  numerous,  one  leaning  against,  and  ter- 
minating near  the  commencement  of  another,  so  as  to  give  an 
imperfect  appearance  of  continuity  throughout  the  bone. 
These  fibres  at  the  extremities  of  the  bones,  are  lost  in  the 
spongy  or  cellular  tissue  which  they  assist  to  form.  The 
transverse  and  oblique,*  serve  to  connect  the  longitudinal  fibres 
together,  and  are  united  with  them  uninterruptedly  upon  their 
sides  ;  in  the  spongy  portions,  they  appear  also,  to  assist  in  the 
formation  of  the  cells.  They  are  both  most  abundant  in  early 
infancy,  and  as  the  bones  increase  in  length,  are  directed  more 
in  the  axis  of  the  bone,  till  the  oblique  seem  nearly  lost  in  the 
longitudinal,  and  the  transverse  become  more  oblique. 
— The  fibres  of  the  different  layers  of  the  compact  bone,  are 
united  to  one  another  more  intimately  upon  the  sides,  than  to 
the  layers  below,  hence  a  bone  exposed  to  the  action  of  the 
weather  or  the  fire,  shells  off  in  scales,  or  in  certain  morbid 
states  during  life,  as  necrosis,  exfoliates  in  layers.f 
— From  these  investigations  the  osseous  tissue,  may  be  justly 
considered  as  formed  of  an  animal  or  membranous  basis,  analo- 
gous to  the  common  cellular  tissue  and  cellular  fibre  in  other 
parts  of  the  body,  and  differing  from  them  only  in  its  being  imbued 
or  incrusted  with  inorganic  earthy  matter,  which  gives  it  ^firm- 
ness and  strength,  but  at  the.  same  time  renders  it  liable  to 
fracture.  The  cells  of  the  bones,  like  those  of  the  cellular  tissue  ^|*. 
of  the  soft  parts  of  the  body,  are  all  imperfect,  having  openings 
by  which  they  communicate  with  one  another,  and  may  be  all 
readily  injected,  with  any  fluid  sufficiently  thin  to  run  ;  and  if 

* 

*  These  represent  the  uniting  pins  of  Gagliardi. 

|  Mr.  Howship  of  England,  from  some  recent  microscopical  observations  on 
the  bones,  has  been  led  to  support  the  opinion  of  Scarpa,  that  the  ultimate  tissue 
of  all  the  bones,  is  reticular  or  cellular.  This  is  evidently  true,  in  regard  to  the 
ultimate  analysis  of  bones,  when  the  course  of  the  fibres  has  been  destroyed  by 
prolonged  maceration,  or  by  suppurative  inflammation. — p. 


CHEMICAL  COMPOSITION    OF    THE    BONES. 

fluid  mercury  be  used  it  will  make  its  way  through  the  vascular 
foramina  to  the  external  surface. — 

The  existence  of  absorbent  vessels,  and  even  of  nerves,  in 
bones,  is  equally  certain  with  that  of  the  blood-vessels,  but  they 
are  not  easily  demonstrated. 

[The  French  anatomists  have  occasionally  traced  branches 
of  the  fifth  pair  of  nerves  going  along  with  the  nutritious  arte- 
ries into  some  of  the  bones  ;  hut  as  yet  no  other  nerves  have 
been  seen  by  them.  M.  Portal  speaks  in  familiar  terms  of  the 
existence  of  both  nerves  and  lymphatics  in  the  bones,  as  if  he 
had  often  noticed  them  ;  he,  however,  has  omitted  to  inform 
us  of  the  source,  from  which  the  former  come.]  fin  the  sound 
state  bones  have  no  sensibility,  but  pain  is  often  felt  in  them 
when  diseased. ) 

— We  cannot  doubt  the  existence  of  the  absorbent  vessels  in 
bones,  since  Cruikshank  and  Scemmering,  affirm  it  from  their 
own  observation,  and  from  their  own  injections.  Breschet,  has 
observed  it  many  times,  and  Bonamy,  in  making  a  mercurial 
injection  of  the  inferior  extremities,  "  was  able  to  follow  them 
for  some  time  in  the  interior  of  the  osseous  tissue." 
— They  possess  (according  to  Bichat,)  a  certain  degree  of  ex- 
tensibility and  retractility,  which  is  developed  so  slowly  as  to 
be  almost  insensible  in  its  progress.  These  properties  are  de- 
monstrated in  the  expansion  of  the  bones  of  the  facje,  from 
tumors  of  the  antrum,  and  in  the  retraction  of  the  sockets  of 
the  teeth,  after  the  loss  or  removal  of  the  latter. — 

Modern  chemistry  has  ascertained  that  the  earthy  matter  of 
'bones  is  principally  a  phosphate  of  lime;  carbonate  of  lime,  in 
a  smaller  quantity,  is  also  found  in  them.  These  earthy  sub- 
stances compose  near  one-half  of  the  weight  of  bones,  and  a 
large  proportion  of  the  remainder  appears  to  be  gelatinous  and 
cartilaginous  matter. 

— The  chemical  composition  of  bones  will  be  found  to  vary, 
in  the  different  ages  of  life,  and  in  some  measure  according  to 
the  individual  bones  selected  for  investigation  ;  the  inner  com- 
pact plate  or  vitreous  table  of  the  cranial  bones,  and  the  petrous 
portion  of  the  temporal,  possessing  a  greater  relative  amount 


CHEMICAL    COMPOSITION    OF    THE    BONES.  23 

of  earthy  matter  than  any  other  bones  in  the  body.  From 
these  causes,  arises  considerable  discrepancy  in  the  analysis 
given  by  different  chemists.  In  early  life  the  relative  propor- 
tion of  earthy  matter  is  at  its  minimum,  the  animal  at  ijs  max- 
imum. In  advanced  age,  the  reverse  holds  good,  when  the 
bones  are  notoriously  brittle  and  liable  to  fracture.  Diseased 
conditions  of  the  system  are  known  to  still  further  modify  these 
proportions  :  in  childhood  the  earthy  matter  may  be  so  much 
diminished  that  the  bones  become  plastic  and  yielding,  as  in 
rickets ;  and  at  later  periods  of  life,  it  preponderates  occasion- 
ally so  much  over  the  animal  as  to  render  them  liable  to  break 
at  the  slightest  shock,  as  in  cases  of  fragilitas  ossium ;  and 
in  some  of  the  venereal  affections,  the  bones  are  rendered  nearly 
as  solid  and  heavy  as  a  piece  of  ebony. 

— The  earthy  matter  of  the  bones  of  the  higher  animals  con- 
sists chiefly  of  phosphate  of  lime,  with  carbonate  of  lime,  and 
a  small  quantity  of  phosphate  of  magnesia,  and  fluate  of  lime. 
— The  phosphate  of  lime  of  the  bones  is  a  subsalt,  according  to 
Miiller,  in  which  the  base  and  acid  are  combined  in  peculiar 
proportions,  and  which  is  always  obtained  when  biphosphate 
of  lime  is  precipitated  by  an  excess  of  ammonia.  The  phos- 
phate of  lime  of  the  urine  is  a  super-salt,  held  in  solution  ;  in 
the  disease  called  mollities  ossium,  it  seems  to  be  excreted  in 
this  state  in  the  urine  in  larger  quantity  than  natural.  The 
following  is  the  result  of  Berzelius'  analysis  of  the  bones  in  man 
and  the  ox  : 

Man.  Ox. 

Cartilage*  completely  soluble  in  water  32.17 


VI  1    1Q    <  *3"30 

Vessels         -             ...  1.13 

Neutral  phosphate  of  lime     -             -  51.04  55.45 

Carbonate  of  lime  11.30  3.85 

Fluate  of  lime                         -  2.00  2.90 

Phosphate  of  magnesia  1.16  2.05 

Soda  with  a  small  proportion  of  cloride  of  }    1  04* 


sodium     -  - 

100.00  100.00 

*  i.  e.  Gelatine. 


24    RESEARCHES  ON  THE  INTIMATE  STRUCTURE  OF  BONE. 

— Schreger  states  that  in  the  bones  of  a  child,  the  earthy 
matter  constitutes  one-half,  that,  in  the  bones  of  an  adult  it 
amounts  to  four-fifths,  and  in  those  of  an  old  person  to  seven- 
eighths  of  the  whole  mass. 

— Fourcroy  and  Vauquelin,  found  no  fluate  of  lime  in  their 
analysis,  but  met  with  some  iron,  manganese,  silex,  alumine, 
and  phosphate  of  ammonia.  The  luminous  appearance  of 
bones  at  night,  when  the  animal  matter  is  undergoing  decom- 
position, is  believed  to  be  owing  to  the  phosphorus  liberated 
from  combination ;  and  in  such  instances,  Bichat  has  found  an 
oily  or  unctuous  exudation  at  the  luminous  points. 
— The  observations  of  M.  Gerdy*  who  has  carefully  investi- 
gated the  structure  of  the  bones,  coincide  in  a  great  degree 
with  the  microscopical  researches  of  the  German  anatomists 
shortly  to  be  noticed.  He  considers  that  there  are  four  distinct 
tissues  in  bone,  which  have  been  confounded  together  up 
to  this  time  ;  the  compact,  the  canaliculated,j*  reticular,  and 
areolar  or  cellular. 

— The  compact  tissue  has  in  certain  bones  a  fibrous  appearance  ; 
its  fibres  appear  longitudinal  in  long  bones,  radiated  or  irregu- 
larly divergent  in  many  of  the  flat.  The  whole  of  this  fibrous 
appearance  is  illusory,  as  Scarpa  asserted,  and  is  owing  to  the 
grooves  or  canals  in  the  compact  portion  of  the  bones  which 
lodge  vessels,  (canals  of  Havers,)  run  longitudinally  in  the 
compact  portion,  and  have  orifices  leading  into  them  from  the 
outer  surface ;  between  the  canals  is  found  projecting  the  pro- 
per structure  of  the  bone,  which  is  necessarily  thin,  and  from 
the  great  number  of  these  vessels,  presents  the  appearance  of 
fibres.  The  vascular  openings  leading  into  the  grooves,  are 
some  perpendicular,  and  some  oblique  in  regard  to  the  surface 
of  the  bones.  They  all  conduct  vessels  into  the  compact  tissue. 
The  compact  tissue,  as  will  be  better  seen  under  the  head  of 
formation  of  bone,  is  primitively  a  compound  of  osseous  tubes 
developed  around  the  vessels.  These  osseous  tubes  which  are 
longitudinal  in  the  long  bones  and  radiated  in  the  flat,  are  so 

*  Bulletin  de  Clinique,  1835-6. 

f  The  canaliculated  tissue  is  formed  by  the  canals  of  Havers,  which  lodge 
blood-vessels. 


GERDY  ON  THE    INTIMATE   STRUCTURE  OF  BONE.  25 

numerous,  fine,  so  closely  compressed  together  and  so  adherent, 
that  their  arrangement  has  escaped   the  observation  of  anato- 
mists.    The  existence  of  these  vessels  in   the  forming  bone  is 
well  understood,  and  they  have  been  injected  with  mercury  by 
Tiedemann  in  the  parietal  bone,*     In  the  adult  healthy  bone, 
they  are  more  difficult  of  detection,  in  consequence  of  *the  dense 
nature  of  the  compact  substance,  in  which   the  vascular  chan- 
nels of  the  bones   and   the  vascular  orifices  on   the  surface  are 
reduced   nearly  to  a   microscopical  size.     But  when   the   bony 
tissue  is  diseased  or  inflamed,  as  in  fractures  or  after  amputa- 
tions, their  existence  is   no  longer  doubtful.     Blood  issues  from 
them  when   cut,  and    the  vascular  orifices   on    the  surface,  as 
well  as  the  canals  in  the  compact  tissue  are  visible  to  the  naked 
eye,  and  in  some  instances  are  said  to  have  been         Fig.  l.f 
as  large  as  a  pigeon's  quill.     Fig.  1,  is   a  view 
of  these  canals,  as   seen  in  a  bone  twenty-five 
days  after  amputation.     When  the  orifices  and 
canals   are   thus  expanded,  the  compact   tissue 
appears    rarefied,    rough    on    its    surface,   more 
light  and  fragile  and  corresponds  in  appearance 
with  the  canaliculated  tissue  of  Gerdy. 
— The  absence  of  fibrous  appearance  on  the  thick  and  mixed  f 
bones  is  dependent   upon  the  direction  of  the  canals,  none  of 
which  run  parallel  to  the  surface,  but   are  all  directed  towards 
the  articular  surfaces  of  the  bones.     In   the  foetus  at  birth  the 
compact   portion  of  these  bones    appears    sieve-like,  from    the 
number  of  vascular  orifices  on   the  surface,  which  lead   perpen- 
dicularly to  the  canals  that  run  towards  the  centre  of  the  bones. 
Hence,  according  to  Gerdy,  the  compact  layer  of  these  bones, 
is    made  up  of  minute  bony  rings,  surrounding   the  numerous 

*  See  Breschet,  plates  of  the  Venous  System. — p. 

f  Fig.  1.  Section  of  the  extremity  of  the  os  femoris,  twenty-five  days  after 
amputation.  It  appears  cribriform  from  the  number  of  irregular  orifices,  be- 
longing to  the  canals  of  Havers  (canaliculi,)  in.  the  compact  portion  of  the  bone. 
The  vessels  which  occupy  these  canals,  are  greatly  enlarged  by  inflammation. 
Cases  of  this  sort  have  been  confounded  by  writers,  with  inflammation  of  the 
veins  of  the  bones. — p. 

\  The  mixed  bones  are  those  which  are  mixed  in  their  character ;  being  partly 
short  and  partly  flat,  as,  the  sacrum,  the  temporal,  maxillary  bones,  &c. 

3 


GERDY  ON  THE  INTIMATE   STRUCTURE   OF  BONE. 


vascular  orifices  which   touch  each  other  at  their  circumference 
like  the  rings  round  the  orifices  of  a  tin  colander.* 
— The  canaliculated  tissue,  is  developed   in   all   the  bones  of 
the  body,  but  is  least  evident  in  the  flat.     It  is   an   assemblage 


of  small  canals  traversed  by 
vessels,  and  has  heretofore 
been  described  as  a  part  of 
the  cellular  or  spongy.  In 
the  long  bones  it  is  found  on 
the  inner  surface  of  the  com- 
pact tissue,  and  separated 
from  the  reticulated  tissue  of 
the  medullary  canal,  by  a 
parchment-like  lamin,  pierced 
with  holes  for  the  passage  of 
anastomosing  vessels.  These 
canaliculi  form  elongated  cavi- 
ties, which  are  slightly  tor- 
tuous, nearly  parallel  with 
one  another,  not  exactly 
rounded,  and  have  their  pa- 
rietes  pierced  with  holes  to 
admit  of  anastomosis  be- 
tween the  vessels  which  line 
them  ;  they  run  in  the  long 
bones  in  the  direction  of  their 
length,  and  in  the  thick  bones, 
from  one  articular  surface  to 
the  other.  They  arise  in  part  6 


Fig.  2.f 


*  This  we  shall  find  is  the  opinion  of  the  microscopists  in  regard  to  the  struc- 
ture of  all  compact  bony  layers. — 

f  Fig.  2.  Vertical  section  of  the  inferior  third  of  the  tibia.  1.  1.  Compact 
tissue  of  the  body  of  the  bone,  becoming  gradually  thinner  towards  the  inferior 
extremity.  2.  2.  Reticulated  tissue  in  the  lower  part  of  the  medullary  cavity 
occupying  the  axis  of  the  cylinder  of  bone.  3.  3.  Canaliculated  tissue,  the  vas- 
cular canals  of  which  deiach  themselves  successively  from  the  compact  walls  of 
the  bone,  and  run  nearly  parallel  with  each  other  towards  the  extremity  of  the 
bone.  4.  4.  Cellular  tissue  of  the  epiphysis,  composed  of  interrupted  canaliculi, 
and  of  tubular  cells,  which  terminate  nearly  perpendicularly  upon  the  articular 
surface.  6.  6.  The  articular  or  sub-cartilaginous  compact  tissue,  extremely  thin. 


GERDY  ON   THE  INTIMATE   STRUCTURE   OF  BONE.  27 

from  the  divisions  of  the  nutritious  foramina,  which  transmit 
the  medullary  vessels  of  the  long  bones,  but  chiefly  from  the 
vascular  (Haversian,)  canals  of  the  compact  tissue,  as  seen  in 
a  vertical  section  of  the  femur  and  tibia,  fig.  2  and  fig.  >J.  where 
the  increase  of  the  canaliculated  structure  is  in  inverse  propor- 
tion to  the  thickness  of  the  compact.  These  canals  unite  together, 
and  divide  again  and  again,  so  that  they  become  increasingly 
numerous  as  they  approach  the  spongy  extremities,  when  they 
separate  from  each  other  and  spread  out  so  as  to  form  a  large 
part  of  these  extremities. 

— The  cellular  or  areolar  tissue  of  Gerdy,  is  formed  in  the 
thick  bones  and  the  extremities  of  the  long  bones  by  the  inter- 
ruptions of  the  canaliculated  tissue,  by  other  canals  arising  from 
the  surface  of  the  bone  which  cross  them  in  an  angular  direc- 
tion, so  as  to  form  quadrilateral  cells,  see  Fig.  3,  No.  1,  the  par- 
titions of  which  are  pierced,  so  that  there  is  a  free  communica- 
tion between  the  vessels  lining  the  different  cells. 
— The  reticulated  tissue  which  was  confounded  by  Bichat  with 
the  canaliculated,  should  be  now  as  it  was  before  his  time  dis- 
tinguished from  it.  So  far  from  being  formed  of  a  canaliculated 
tissue  for  the  purpose  of  containing  vessels,  it  consists  only  of 
a  network  of  bony  filaments  for  the  purpose  of  supporting  a 
delicate  cellular  membrane  called  the  medullary  which  is 
thrown  into  the  form  of  cells  to  retain  the  fat  or  marrow,  and 
which  is  very  vascular.  It  is  found  chiefly  in  the  cavities  of 
the  long  bones,  and  terminates  short  of  the  extremities  in  a 
point,  see  Fig.  3,  6,  while  the  canaliculated  tissue  continues  to 
expand.  This  tissue  is  beautifully  developed  in  the  long  bones 
of  the  horse,  but  scarcely  exists  at  all  in  those  of  the  bullock. 
- — Vessels  of  the  bones.  All  anatomists  admit  three  kinds  of 
vessels  in  the  bones ;  those  of  the  compact  tissue,  those  of  the 
cellular  tissue,  those  of  the  medullary  canal. 
— Those  of  the  compact  tissue  are  very  fine  and  very  nume- 
rous ;  they,  penetrate  it  in  great  numbers,  after  having  divided 


Very  generally  it  is  deficient  in  places  on  the  articular  surface  of  bones,  so  as  to 
leave  the  cells  of  the  spongy  tissue  and  their  vascular  canals  naked  when  the 
cartilage  is  removed.  7.  Internal  malleolus. — p. 


28  GERDY  ON   THE  INTIMATE   STRUCTURE  OF  BONE. 

Fig.  3.* 


to  capillary  minuteness  in  the  periosteum.  The  diameter  of 
these  little  vessels,  where  they  enter  the  bone,  has  been  calcu- 
lated to  be  about  one-twentieth  part  of  a  line.  The  drops  of 
blood  which  collect  when  the  periosteum  is  stripped  from  the 

*  Fig.  3.  Vertical  section  of  the  os  femoris.     1.  1.  Tubular  cells  perpendicular 
to  the  articular  surface  of  the  bone  ;  sometimes  these  cells  are  chiefly  round. 

2.  Cartilaginous  lamin   separating  the  epiphysis  from  the  shaft  of  the  bone. 

3.  Vertical  canal  opening  by  one  or  more  foramina,  in  the  fossa  at  the  top  of  the 
trochanter,  and  anastomosing  with  the  canals  of  the  canaliculated  tissue.     It 
lodges  one  of  the  vessels  of  the  cellular  tissue ;  which  penetrate  by  the  extremity 
of  the  body  of  the  long  bone.    4.  4.  Vascular  canaliculi,  which  run  obliquely 
upwards  and  inwards  towards  the  lamen  of  the  epiphysis,  where  the  cartilage 
begins  to  be  removed,  and  the  consolidation  of  the  epiphysis  and  shaft  has  com- 
menced.    5.  5.  Canaliculi  of  the  upper  part  of  the  body  of  the  bone,  which  are 
directed  towards  the  axis  of  the  bone,  and  which  anastomose  with  the  vascular 
canal  indicated  at  3.     6.  Conical  termination  of  the  reticulated  tissue  of  the 
medullary  canal. — p. 


GERDY  ON   THE  INTIMATE   STRUCTURE  OF  BONE.  29 

recent  bone,  indicate  the  position  of  these  vessels.  Having 
entered  the  compact  tissue,  they  spread  in  its  channels  (canals 
of  Havers,  canaliculi  of  Gerdy^)  which  are  imperceptible 
without  a  microscope  in  a  healthy  bone,  but  beconae,  very 
manifest  in  disease. 

— Those  of  the  medullary  canal  enter  usually  by  a  single  large 
foramen,  give  off  some  branches  to  the  canaliculi  in  their  course, 
and  having  reached  the  medullary  or  central  cavity,  divide  into 
two  branches,  which  run  in  opposite  directions  towards  the 
extremities  of  the  bone.  These  branches  divide  and  subdivide 
very  minutely  in  the  medullary  membrane,  and  anastomose 
very  freely  with  the  vessels  of  the  canaliculated  tissue  upon 
the  side,  and  in  the  adult,  (after  the  cartilage  which  separates 
the  epiphysis  from  the  body  of  the  bone  has  been  removed,) 
with  the  cellular  tissue  of  the  extremities. 

— Those  of  the  cellular  tissue,  that  is  to  say  the  vessels  of  the 
extremities  of  the  long  bones  and  the  large  vessels  of  the  other 
bones,  penetrate  from  the  surface  by  foramina  much  larger  than 
those  of  the  compact  bone,  and  occasionally  under  the  form  of 
distinct  canals.  They  are  very  numerous.  I  have  counted  145 
on  the  lower  end  of  the  femor,  25  upon  a  vertebra,  and. 30  on  the 
os  calsis.  They  anastomose  intimately  with  the  other  two  orders 
of  vessels,  and  are  particularly  abundant  near  the  articular  sur- 
face of  the  bones,  where  they  form  the  tubular  cells,  and  as  some 
suppose,  directly  or  indirectly  assist  in  the  formation  of  the 
articular  cartilages,  which  many  have  considered  a  simple  pro- 
duct of  excretion  like  the  nails  or  hair.  All  the  vessels  are  sur- 
rounded in  the  canals  by  a  cellular  tissue,  more  or  less  delicate 
loose  and  filled  up  with  a  fatty  or  oily  matter,  which  is  least 
abundant  in  the  compact  tissue  where  the  canals  are  very  small. 
No  other  nerves  except  those  which  accompany  these  vessels 
are  believed  to  enter  the  substance  of  bone.  These  facts  in 
regard  to  the  structure  of  bone  are  supported  both  by  observa- 
tion and  reasoning.  The  microscope  shows  us  thousands  of 
vessels  in  the  healthy  state  entering  into  the  substance  of  the 
bones.  Inflammation  attended  with  vascular  congestion  develops 
and  renders  them  so  obvious  as  to  be  appreciated  by  the 
3* 


30  DEUTSCH    AND    MIESCHER 

unassisted  eye,  the  slightest  irritation  with  a  probe  will 
cause  them  to  bleed  freely,  and  heat  applied  to  a  section  of  a 
recent  bone,  will  develop  the  fatty  or  oily  matter  even  in  the 
compact  portion.  From  the  complexity  of  their  organization, 
and  the  frequency  and  importance  of  their  diseases,  bones  demand 
from  the  student,  more  earnest  study,  at  least  in  regard  to 
their  general  anatomy  than  is  usually  given. — 
— Deutsch,*  under  the  direction  of  Purkinje,  and  Miescherf  of 
Berlin  whose  investigations  were  made  prior  to  those  of  Gerdy, 
have  arrived  at  nearly  similar  conclusions  in  regard  to  the 
structure  of  bone.  In  very  thin  transverse  sections  of  long 
bones,  which  had  been  macerated  in  dilute  acid,  they  disco- 
vered the  circular  orifices  of  the  longitudinal  canals  in  the  com- 
pact portions  of  the  bone ;  and  in  thin  longitudinal  sections 
the  canals  were  seen  divided  in  the  direction  of  their  length.  (See 
Figs.  4  and  5.)  The  canals,  according  to  these  observers,  com- 
municate here  and  there  with  each  other,  and  constitute  the 
longitudinal  and  transverse  canals  of  Havers,  and  which  are 
described  by  Lewenhceck,  as  his  third  and  fourth  kinds  of 

pores. 

Fig.  4.J 


— These  canals  are  rilled  with  yellowish  medullary  or  adipose 
matter,  in  which  according  to  Miescher,  are  seen  many  minute 
capillary  vessels,  when  successfully  injected  after  the  method 
of  Krause. 

*  De  pentiori  ossium  stractura  observations.    Vratislavise,  1834. 

f  De  ossium  genesi,  structura  et  vita.     Berolini,  1836. 

$  Fig.  4.  Is  a  longitudinal  section  of  a  long  bone,  magnified  one  hundred 
times,  a.  One  of  the  longitudinal  canals  not  fully  exposed,  b.  b.  Longitudinal 
canals,  c.  c.  These  canals  partially  cut  across,  so  as  to  exhibit  the  concentric 
lamellae  which  surround  each  one.  d.  d.  Transverse  canals  joining  the  others. 
The  straight  lines  near  the  margins  of  the  cut,  are  the  lamellae  divided  in  the 
direction  of  their  length,  which  surround  the  canals.  The  spots  seen  are  the 
bony  corpuscles,  not  sufficiently  magnified  to  render  them  distinct. 


ON  THE  INTIMATE  STRUCTURE  OF  BONE.  31 

Fig.    5.* 


— In  the  transverse  section,  each  of  the  orifices  of  the  canals, 
Fig.  5,  is  seen  surrounded  by  ten  or  fifteen  concentric  lines, 
which  on  examining  the  longitudinal  section,  Fig.  4,  are  found 
to  be  as  many  lamellae  running  the  whole  length  of  the  canal, 
and  each  about  the  ?|5th  part  of  an  inch  in  diameter,  accord- 
ing to  the  microscopical  measurement  of  Deutsch.f  The  spaces 
in  the  transverse  section  of  the  bone,  not  occupied  by  the  lon- 
gitudinal canals  and  their  concentric  lamellae,  are  filled  by 
other  lamellae,  which  form  larger  concentric  rings  round  the 
great  medullary  cavity.  The  diameter  of  the  canals  of  Havers, 
according  to  Miescher,  varies  from  ^th  to  ^ili  of  an  Eng- 
lish inch. 

— In   the  flat  bones   the  canals  with  their  lamella,  run  parallel 
with  the  surface  of  the  bone.     In  the  long  bones,  the  longitu- 
dinal canals  are  directed  obliquely  into  the  central  cavity. 
— In  the  lamellae  concentric   to  the  canals,  there  is  an  appear- 
ance of  dots  or  short  lines,  which   do  not  occupy  the  whole 

*  Fig.  5.  Is  a  transverse  section  of  one  of  the  flat  bones  of  the  cranium,  mag- 
nified one  hundred  times,  a.  Compact  substance  or  table  of  bone,  expanding 
into  diploe.  b.  b.  c.  c.  Vasculo-medullary  canals  of  the  compact  portion,  cut 
across,  d.  Transverse  communicating  canals,  between  these  and  the  larger 
canals  or  cellular  cavities  of  the  diploe.  e.  Diploic  cells  communicating  with 
others  at  /.  Diploic  cells  like  the  canals  of  the  compact  portion,  are  surrounded 
with  concentric  striae  or  lamellae,  and  are  in  fact  only  amplified  vasculo-medul- 
lary  canals.  The  spots  upon  the  surface,  are  the  bony  corpuscles. 

f  Some  modern  observers  have  made  the  diameter  or  thickness  of  each  of 
these  lamellae,  much  less  than  that  stated  by  Deutsch.  Mr.  Wilson  states  it  to 
be  not  more  than  the  ^5^  a  measurement  which  appears  to  me  to  err  much 
on  the  minimum  side — . 


32  OF    THE    PERIOSTEUM. 

thickness  of  each  lamellae,  and  which  Deutsch,  supposed  to  be 
extremely  minute  tubes.  Some  of  these  dots  or  lines,  see  Fig. 
5,  appear  to  transverse  more  than  one  lamella,  though  the 
majority,  as  Miescher  describes  them,  are  very  short,  and 
appear  like  the  separations  between  the  granules  of  the  carti- 
lage of  the  bones,  from  which  the  calcerous  portions  had  been 
removed.*  The  result  of  the  observations  of  Miescher,  is : 
— 1st.  That  the  spongy  structure  of  bones,  is  nothing  but  an 
amplification  of  the  canaliculi,  as  is  shown  by  Gerdy. 
— 2d.  That  the  medullary  canal,  as  shown  by  its  formation 
and  name,  is  provided  for  the  purpose  of  union  or  anastomosis, 
between  these  enlarged  canaliculi,  and, 

— 3d.  That  therefore,  the  canaliculi,  girdled  with  concentric 
lamellae  and  containing  a  medulla,  composed  of  a  great  body 
of  vessels,  is  the  primary  element  or  form  of  the  osseous  tissue, 
which  is  subsequently  more  fully  developed. 
— Scarpa  is  therefore  correct  in  saying  that  the  solid  parts  of 
bone,  are  formed  of  the  cellular  structure  in  a  more  compacted 
state.  The  reticulated  tissue,  which  forms  a  sort  of  link 
between  the  cellular  substance  and  the  medullary  cavity,  and 
the  osseous  filaments  which  project  every  where  from  the 
parieties  of  the  cavity  into  the  medulla,  are  the  remains  of  the 
walls  of  the  cells,  the  integrity  of  which  is  impaired  in  conse- 
quence of  the  enlargement  of  the  orifices  by  which  they  com- 
municate together. — 

Of  the  Periosteum. 

Bones  are  invested  with  a  firm  membrane  .denominated 
periosteum,  which  is  of  a  fibrous  texture,  and  in  some  places 
may  be  separated  into  different  lamina.  The  external  surface 
of  periosteum  is  connected  with  the  contiguous  parts  by  cel- 
lular membrane ;  the  internal  surface  is  connected  with  the 
bone  by  a  great  number  of  fibres  and  blood-vessels.  The 
orifices  of  these  vessels  become  apparent,  when  the  periosteum 
is  separated  from  bones  in  the  living  subject. 


*  Subsequent  microscopical  observations,  as  will  be  shown  further  on,  have 
confirmed  this  supposition  of  Deutsch. — p. 


MEDULLARY  MEMBRANE  OR  INTERNAL  PERIOSTEUM.  33 

This  membrane  covers  the  whole  bony  surface,  except  those 
parts  which  are  invested  by  cartilages,  and  the  capsular  liga- 
ments of  joints,  those  which  are  occupied  by  the  insertion  of 
tendons  and  ligaments,  and  the  bodies  of  the  teeth.  It  appears 
most  intimately  connected  with  the  surfaces  of  spongy  oones, 
and  the  extremities  of  the  long  bones.  In  a  sound  state  it  has 
very  little  sensibility ;  but  in  some  cases  of  disease  it  appears  to 
be  very  sensible  ;  of  course  it  must  be  supplied  with  nerves, 
although  several  expert  anatomists  have  declared  they  could  not 
trace  them. 

It  is  probable  that  the  principal  use  of  the  periosteum  is  to 
transmit  vessels  to  the  bones  for  their  nourishment ;  but  death  or 
exfoliation  of  the  surface,  does  not  always  take  place  when  the 
periosteum  is  removed  from  a  portion  of  bone.* 
— This  membrane  presents  a  polished,  pearly  white  appear- 
ance, when  examined  in  the  recent  bone.  It  has  received 
different  names  according  to  the  parts  which  it  covers,  though 
its  structure  is  nearly  uniform  throughout.  Thus,  when  it 
covers  the  exterior  surface  of  the  bones  of  the  cranium  it  is 
called  pericranium ;  when  it  covers  the  cartilages,  perichon- 
drium  ;  and  when  it  covers  the  bones  with  the  exception  of 
those  of  the  head,  periosteum. 

— In  infancy  the  periosteum  is  soft,  thick,  and  spongy,  and 
may  be  readily  separated  from  the  bones.  In  adult  life  it  is 
more  firm  and  compact,  and  is  often  so  intimately  united  to  the 
bones  as  to  be  detached  with  difficulty  from  them.  In  old  age 
it  is  extremely  dense,  and  becomes  not  unfrequently  ossified  at 
its  internal  surface.  Its  vascularity,  which  is  at  first  rather 
obscure,  also  gradually  increases  as  life  advances,  but  in  old  age 
it  again  diminishes.f 

Of  the  Internal  Periosteum  or  Medullary  Membrane. 
— This  membrane  is   particularly  well   marked   in  the  cavities 

*  Dr.  Physick  thinks  that  the  periosteum  frequently  prevents  the  bones  from 
participating  in  contiguous  disease,  as  the  pleura  turns  off  an  abscess  inthe  parie- 
tes  of  the  thorax  from  its  cavity,  or  the  peritoneum  from  the  cavity  of  the 
abdomen. — 11. 

f  Anat.  Phys.  and  Diseases  of  Bones  and  Joints.    By  S.  D.  Gross,  M.  D. 


34  MEDULLARY  MEMBRANE  OR  INTERNAL  PERIOSTEUM. 

of  the  long  bones,  where  it  forms  a  thin,  delicate,  pellucid, 
vascular  membrane,  lining  the  sides  of  the  cavities  of  the  reticu- 
lated tissue,  in  which  it  forms  vesicles,  that  contain  the  marrow. 
— The  lining  membrane  of  the  cells  in  the  spongy  portion  of 
the  bones  is  still  more  delicate  in  its  structure,  and  more  difficult 
of  demonstration,  and  has  been  supposed  by  many  anatomists 
to  be  formed  only  from  the  coats  of  the  blood-vessels  which 
anastomose  thousands  of  times  with  each  other  in  the  interior 
of  these  bones.  Its  office,  however,  is  precisely  similar  to  that 
of  the  membrane  in  the  cavity  of  the  long  bones,  to  lodge  the 
fatty  or  medullary  matter  which  is  furnished  by  exhalation. 
It  is  very  inflammable/  burning  with  a  beautiful  blue  tinge,  and 
an  oily  disagreeable  odor,  fluid  during  life,  but  presents  itself 
after  death,  under  the  form  of  brilliant  granules  of  solid  fatty 
matter.  When  death  has  taken  place  from  some  wasting 
disease  as  dropsy  or  consumption,  the  fat  is  removed  by 
absorption,  and  its  place  is  supplied  by  a  watery  fluid  which 
renders  the  bones  less  greasy  and  more  valuable  as  cabinet 
preparations.  This  medullary  substance  as  has  been  before 
observed  is  also  found  with  the  vessels  in  the  canals  of  the  com- 
pact portions  of  bone< — 

At  the  extremities  of  the  long  bones,  the  formina  for  the 
transmission  of  the  blood-vessels  and  fibres  are  much  larger 
than  they  are  in  the  middle ;  but  there  is  an  oblique  canal  near 
the  middle  of  these  bones,  which  transmits  vessels  to  this 
membrane  in  the  interior  of  the  bones  called  nutritious  or 
medullary. 

The  surface  of  the  internal  cavities  and  cells  of  bones  it  will 
then  be  seen,  is  lined  by  a  membrane  more  delicate  and  more 
vascular  than  the  periosteum,  which  contains  the  medullary 
matter  that  is  always  found  in  their  cavities.  [This  is  the* 
internal  periosteum  or  the  medullary  membrane  of  the  bones. 
M.  Portal  denies  that  it  exists  as  a  distinct  membranous  sac, 
but  asserts,  that  it  is  derived  from  the  envelop  of  the  vessels 
which  is  sent  in  along  with  them  from  the  periosteum.] 

It  has  been  said  that  in  some  circumstances  this  membrane 
has  had  great  sensibility,  but  the-  reverse  is  the  case  in  com- 
mon. 


MEDULLARY  MEMBRANE  OR  INTERNAL  PERIOSTEUM.  35 

The  medullary  matter  in  the  large  cavities  of  bones  has  a 
strong  resemblance  to  adeps.  That  which  is  in  the  cells,  at  the 
ends  of  the  long  bones,  appears  more  fluid.  In  young  animals 
it  is  slightly  tinged  with  a  red  color.  *s 

— The  chemical  properties  of  the  adipose  or  medullary  sub- 
stance of  the  bones  consist  according  to  Berzelius  of  the  fol- 
lowing ingredients : 

Pure  adeps  or  marrow  96 

Membrane  and  blood-vessels  -         1 

Albumen  - 

Gelatine 

Extractive  and  peculiar  matter 

Water 


100 

— The  character  of  this  substance  differs  somewhat  at  the  dif- 
ferent stages  of  life  ;  it  is  of  a  thin  aqueous  consistence  and  of 
a  reddish  color  in  the  infant ;  of  the  consistence  and  presenting 
after  death  somewhat  the  appearance  of  butter  in  the  central 
cavities  of  the  bones,  and  of  a  red  semi-fluid  appearance  in  the 
spongy  tissue  of  the  bones  of  the  adult ;  in  old  age  it  has  some- 
thing of  a  rancid  smell,  and  is  of  a  deep  yellow  color.  The 
adeps  of  the  bones  was  supposed  at  one  time  to  contribute  to 
the  flexibility,  tenacity,  and  nourishment  of  the  Irenes,  but  it  is 
now  generally  believed  to  be  deposited  upon  the  same  principles, 
as  fat  in  other  parts  of  the  body,  when  nutritive  matter  is  super- 
abundantly elaborated  by  the  digestive  organs,  and  is  held  in 
reversion,  as  an  aliment  for  the  future  wants  of  the  economy, 
during  temporary  inanition  from  sickness  or  other  causes. 
— The  deposit  of  fat  in  bones  is  not  universal  among  animals. 
In  birds  the  central  cavity  of  the  long  bones,  is  filled  only  with 
air  which  is  introduced  into  them  from  the  lungs,  and  serves  ! 
greatly  to  diminish  their  specific  gravity,  and  facilitates  their/ 
evolutions  in  the  atmosphere. 

— It  is  found  in  great  quantity  in  the  bones  of  the  head  of  the 
wwerocep/m/ws,  or  sperm  whale,  far  out  of  the   pro- 


36  CARTILAGES  AND   THEIR  STRUCTURE. 

portion  required,  if  its  object  only  was  that  of  nourishing  the 
bones. 

— Its  purpose  in  this  animal,  besides  being  a  deposit  of  aliment 
in  reserve,  is  believed  to  be  that  of  buoying  up  its  head  to  ena- 
ble it  to  respire  with  greater  freedom. — 

Cartilages  and  their  Structure. 

CARTILAGES  are  white  elastic  substances,  much  softer  than 
bones,  in  consequence  of  a  smaller  quantity  of  earth  entering 
into  their  composition. 

Their  structure  is  not  so  evidently  fibrous  as  that  of  bones  ; 
yet  by  long  maceration,  or  by  tearing  them  asunder,  a  fibrous 
disposition  is  perceptible. 

In  articular  cartilages  their  fibres  are  parallel  to  each  other, 
and  directed  towards  the  cavities  of  the  respective  joints. 

Their  vessels  are  extremely  small,  though  they  can  be  readily 
injected  in  cartilages  where  bone  is  beginning  to  form.  The 
vessels  of  the  cartilages  of  the  joints,  however,  seem  entirely  to 
exclude  the  red  blood  ;  no  anatomist  having  yet  been  able  to 
inject  them.  They  have  no  cancelli,  nor  internal  membranes, 
for  lodging  marrow  ;  no  nerves  can  be  traced  into  them  ;  nor  do 
they  possess  any  sensibility  in  the  sound  state. 

Upon  their  surface,  there  is  a  thin  membrane  termed  peri- 
chondrium,  which  in  cartilages  supplying  the  place  of  bone,  as 
in  those  of  the  ribs  or  at  the  ends  of  long  bones  in  children,  is 
a  continuation  of  the  periosteum,  and  serves  the  same  general 
purposes  to  cartilage  as  this  does  to  bone. 

Upon  the  surface  of  articular  cartilages,  the  perichondrium  is 
a  reflection  of  the  inner  surface  of  the  capsular  ligament,  and  is 
so  very  thin,  and  adheres  so  closely,  as  to  appear  like  part  of 
the  cartilage  itself.* 

One  set  of  cartilages  supplies  the  place  of  bone,  and  by  their 
flexibility  admit  of  a  certain  degree  of  motion,  while  their 

*  The  articular  cartilages  are  the  only  ones  not  provided  with  a  fibrous  peri- 
chondrium. The  synovial  membrane  which  is  supposed  to  cover  them  by  being 
reflected  from  the  inner  face  of  the  capsular  ligament,  is  said  to  supply  the  place 
of  perichondrium. — p. 


CARTILAGES  AND  THEIR  STRUCTURE.  37 

elasticity  recovers  their  natural  position,  as  in  the  nose,  larynx, 
cartilages  of  the  ribs,  &c. 

Another  set,  in  children,  supplies  the  place  of  bone,  until  bone 
can  be  formed,  and  affords  a  nidus  for  the  osseous  fibres  <p  shoot 
into,  as  in  the  long  bones  of  children. 

A  third  set,  and  that  the  most  extensive,  by  the  smoothness 
and  lubrication  of  their  surface,  allow  the  bones  to  move  readily, 
without  any  abrasion,  as  in  the  cartilages  of  the  joints. 

A  fourth  set  supplies  the  office  both  of  cartilage  and  ligament, 
giving  the  elasticity  of  the  former  and  the  flexibility  of  the 
latter,  as  in  the  bones  of  the  spine  and  pelvis. 

— Next  to  the  bones,  the  cartilages  form  the  hardest  tissue  in 
the  body.  On  first  inspection  they  do  not  appear  to  present 
any  sort  of  internal  organization.  They  appear  homogenous 
in  their  texture  and  inorganic.  When  more  carefully  inspected, 
however,  and  especially  in  the  articular  cartilages,  a  particular 
structure  is  apparent. 

— According  to  De  Lasone  and  Hunter,  the  articular  cartilages 
are  composed  of  fibres  implanted  perpendicularly  to  the  surface 
of  the  bones,  and  parallel  with  each  other,  like  the  villior  threads 
upon  a  piece  of  velvet.  In  this  manner  the  cartilages  covering 
the  bones  forming  the  joints,  supposed  to  be  invested  with 
the  synovial  membrane,  rub  against  each  other,  not  upon  the 
sides,  but  upon  the  ends  of  the  fibres,  which  brings  the  elas- 
ticity of  the  latter  into  play.  The  perpendicular  direction  of 
these  fibres  may  be  made  apparent  by  maceration,  or  by 
sawing  down  a  recent  bone,  and  splitting  through  its  carti- 
lage— and  they  were  believed  by  Beclard,  to  constitute  the 
numerous  free  floating  flocculi,  which  are  seen  on  the  surface 
of  cartilage  in  its  transformations  from  disease. 
— It  is  very  probable  that  there  is  some  cellular  tissue  in  the 
composition  of  cartilages :  when  carefully  incinerated,  the  re- 
mains present  a  cellulated  appearance.  Its  existence  is  rendered 
still  more  probable,  from  the  cartilages  being  developed  in  the 
foetus  in  a  mould  of  cellular  tissue  ;  and  from  fleshy  granulations, 
having  been  seen  occasionally  to  spring  from  the  surface  of  some 
4 

x  ^ 

.•  %  ,*  i:%    *         «..    .  fr  •  %%%'":>    . \--\X\ 

7SX--  0V. 

•% .  .      / 


38  CARTILAGES  AND  THEIR  STRUCTURE. 

of  them  in  various  parts  of  the  body,  though  not  from  the  ar- 
ticular. 

—  When  a  recent  cartilage  is  cut,  a  whitish  juicy  fluid  is  seen  to 
exude  from  its  substance,  which  must  get  into  it,  by  imbibition 
from  the  surrounding  parts,  or  as  has  been  thought  more  proba- 
ble, be  carried  into  it,  by  white  vessels,  too  small  to  admit  more 
than  the  serous  portions  of  the  blood.     If  inflammation  take  place, 
which  is  admitted  in  many  carlilages,  though  not  as  yet  proven 
to   exist  in  those  of  the  joints,  it  differs  from  ordinary  inflam- 
mation  as  these  vessels  are  never  so   dilated,  as   to  admit  the 
red  globules,  and   present  a   red  appearance.     No  lymphatics 
have    ever    been    traced    into    them,    though    Mascagni   was 
disposed  to  consider  them  as  formed  entirely  of  these  vessels. 
Nor  have   nerves  been   found  in  them,  the   very  existence   of 
which  in  these  parts,  though  so  necessary  to  the  perfection  of 
other  organs,  would  have  unfitted  them  for  their  office.     Hence 
we  find  them  smooth,  so  as  to  move  upon  one  another  without 
friction,  destitute  of  nerves,  so  as  to  bear  pressure  without  sen- 
sation, and  feebly  supplied  with  vessels,  so  as  to  be  little  prone 
to  inflammation,  if  they  be  not,  as  Gerdy  has  suggested,  a  mere 
secretion  like  the  hair  and  .nails.     Hence  they  are  enabled  to 
bear    exposure    to    the    air   for   a    considerable    time   without 
change,  as  stated  by  Velpeau,  and  to  exist  unharmed  frequently 
in  the  midst  of  gangrene. 

—  According  to  J.  Davy,  their  chemical  composition  is  55.  parts 
in  the  hundred  of  water,  44.5,  of  albumine,  and  .5  of  phosphate 
of  lime.     As  in   the   bones,  however,  the  chemical  proportions 
vary  at  the  different  periods  of  life.     They  are  nearly  fluid  in 
the  foetus,  contain   a  large  amount  of  fluid   in  youth,  have   the 
proportions  given  above  at  puberty,  and  a  much  larger  amount 
of  earthy  matter  in  old  age.     In  fact,  with  some  few  exceptions 
in  the  joints,  they  all   have  a  natural  tendency  to  ossify  as  life 
advances. 

—  The  structure  of  cartilage  is,  however,  not  fully  understood  ;  that 
they  share  in  some  manner  in  the  general  circulation  of  the  body, 
is  rendered  probable  by  their  being  colored  yellow  in  jaundice  ; 
and  that  they  are  not  reddened  like  the  bones  when  an  animal  is 


HO  .......  •  ---in 


ACCIDENTAL  DEVELOPMENT  OF  CARTILAGES.  39 

fed  upon  madder,  is  said  by  Beclard,  to  be  owing  to  tbe  small 
quantity  of  phosphate  of  lime  which  they  contain,  and  with 
which  this  coloring  matter  only  has  affinity.  They  participate 
too  in  the  ulcerative  process  in  many  parts  of  the  body,  as  in 
those  of  the  nose,  and  as  I  have  many  times  seen,  in  tnose  of 
the  larynx  and  trachea. 

— All  cartilages  are  divided  into  two  classes,  temporary  or 
ossescent,  and  permanent,  a  distinction  which  though  not  per- 
fectly exact,  is  nevertheless  very  convenient  for  the  purposes 
of  study.  The  temporary  cartilages,  (cartilag.  temporaries) 
are  those  employed  in  the  development  of  the  bones,  those  of 
which  the  models  of  the  bones  are  all  formed  in  the  foetus,  and 
which  gradually  as  the  infant  advances  in  growth  give  place  to 
bony  matter.  The  substitution  of  bony  matter  for  the  cartilagi- 
nous, is  completed  about  the  period  of  puberty. 
— The  permanent  cartilages  (cartilag.  permanentes)  are  devel- 
oped at  an  early  period  of  life  like  the  former,  but  have  little 
tendency  to  undergo  ossification,  and  retain  their  cartilaginous 
character  for  the  whole  or  the  greatest  part  of  life.  These  com- 
prise, the  articular  and  costal  cartilages,  those  of  the  larynx, 
eustachian  tube,  auditory  meatus,  etc.  Some  of  these  have  a 
stronger  tendency  than  the  rest  to  ossify,  as  those  of  the  larynx 
and  ribs,  which  are  frequently  found  after  the  fortieth  year  of 
life,  converted  into  bone. 

Accidental  development  of  Cartilages. 

— In  almost  every  one  of  the  different  tissues  of  the  body,  car- 
tilages have  been  occasionally  met  with,  but  in  general  only  after 
the  middle  period  of  life,  when  from  their  having  apparently 
no  fixed  laws  of  development,  they  have  been  called  acci- 
dental. 

— 1st.  They  are  found  in  the  form  of  plates  of  greater  or  less 
size,  adherent  by  both  surfaces  to  the  membranes  between 
which  they  are  formed  ;  in  the  arteries,  where  these  plates  are 
most  frequently  met  with,  they  are  attached  on  their  inner 
surface  to  the  serous  lining  membrane,  and  on  their  outer  to  the 
middle  coat  of  the  vessel. 


40  FORMATION    OF    BONE. 

— 2d.  They  are  frequently  met  with  in  the  form  of  roundish  or 
irregular  masses  in  the  substance  of  the  different  organs,  as  the 
arteries,  lungs  and  ovaries. 

— 3d.  Under  the  form  of  smooth  flattened  concretions,  formed 
originally  according  to  Meckel  on  the  outer  side  of  the  synovial 
membrane  of  the  joints,  and  which  develop  themselves  towards 
the  centre  of  the  cavity  of  the  joints,  till  their  attachment  to 
the  membrane  is  stretched  out,  so  that  it  becomes  a  mere  pedicle, 
which  not  unfrequently  breaks  *off.  In  this  way  is  formed  the 
loose  cartilages  often  met  with  in  the  knee  joint. 
——All  these  accidentally  developed  cartilages  have  a  tendency 
to  be  converted  into  bone,  and  which  are  then  called  accidental 
ossifications. — 

Of  the  Formation  of  Bone. 

The  generality  of  bones,  and  particularly  those  which  are 
long,  are  originally  formed  in  cartilage ;  some,  as  those  of  the 
skull,  are  formed  between  membranes,  and  the  teeth  in  distinct 
bags. 

When  ossification  is  about  to  begin  in  a  particular  part  of 
a  cartilage,  most  frequently  in  the  centre,  the  arteries,  which 
were  formerly  transparent,  become  dilated,  and  receive  the  red 
blood  from  which  the  osseous  matter  is  secreted.  This  matter 
retains,  for  some  time,  the  form  of  the  vessels  which  gave  it 
origin,  till  more  arteries  being  by  degrees  dilated,  and  more 
osseous  matter  deposited,  the  bone  at  length  attains  its  com- 
plete form. 

During  the  progress  of  ossification,  the  surrounding  cartilage 
by  degrees  disappears  ;  not  by  being  changed  into  bone,  but 
by  an  absorption  of  its  parts,  the  new-formed  bone  occupying 
its  place. 

The  ossification  of  broad  bones,  as  those  of  the  head,  begins 
by  one  or  more  points,  from  which  the  osseous  fibres  issue  in 
rays,  as  seen  in  Fig.  6. 

The  ossification  of  long  bones,  as  in  those  of  the  extremities, 
begins  by  central  rings,  from  which  the  fibres  extend  towards 
the  ends  of  the  bones. 


FORMATION    OF    BONE.  41 

The   ossification    of   spheri-formed   bones,         Fig.  6.* 
begins  by  one  nucleus,  as  in   the  wrist ;  and 
that  of  irregularly  shaped  bones  by  different 
nuclei,  as  in  the  vertebrae. 

Some  bones  are  completely  formed  at  the 
time  of  birth,  as  the  small  bones  of  the  ear. 

The  generality   of  bones    are  incomplete 
until  the  age  of  puberty,  or  between  the  fifteenth  and  twentieth 
year,  and  in  some  few  instances  until  a  later  period. 

In  children,  many  parts  of  bones,  particularly  the  ends  of 
long  bones,  are  distinct  from  the  bodies ;  they  are  called 
epiphyses,  and  can  be  readily  separated  from  the  bodies  of 
bones,  by  boiling,  or  by  maceration  in  water. 

The  epiphyses  begin  to  appear  after  the  body  of  the  bone  is 
ossified,  and  are  themselves  ossified   at  seven   or  eight  years  of ,' 
age,  though   their  external  surface  is  still  somewhat  cartilagi- 
nous. 

They  are  joined  to  the  body  of  the  bone  by  the  cartilages, 
which  are  thick  in  children,  but  gradually  become  thinner  as 
ossification  advances,  till  at  last,  in  the  adult,  the  external 
marks  of  division  are  not  to  be  seen,  though  frequently  some 
mark  of  distinction  may  be  observed  in  the  cancelli. 
— The  development  of  bones  is  the  final  result  of  several  suc- 
cessive changes.  In  the  foetus  the  bone  is  at  first  represented, 
by  a  soft  gelatinous  mass,  continuous  throughout  as  one  piece, 
and  in  which  there  is  no  appearance  of  joints.  The  consistence 
of  this  matter  gradually  increases,  and  presents  a  cartilaginous 
appearance,  about  the  second  or  third  months  of  foetal  life.  At 
the  same  period  a  separation  is  manifested  at  the  place  of  the 
joints.  A  third  change  takes  place  in  the  cartilage,  which  is 
that  of  ossification ;  this  commences  in  some  of  the  bones, 
between  the  second  and  third  months  of  foetal  life,  at  various 

*  Parietal  boss  of  the  infant  at  birth  magnified,  showing  the  central  point  of 
ossification.  At  first  sight  the  vascular  canals,  resemble  radiated  lines,  but  with 
a  little  attention,  they  will  be  found  to  be  vascular  channels,  slightly  tortuous, 
and  originating  near  the  centre  of  the  boss  or  protuberance  from  the  foramina 
in  Ihe  newly  formed  bone. — p. 

4* 


42  FORMATION    OF    BONE. 

periods  in  other  bones,  in  many  not  till  long  after  birth,  and  is 
not  completed  in  all  the  bones  of  the  body  till  near  the  period 
of  puberty. 

•"""  In  the  metamorphosis  of  cartilage  to  bone,  the  white  and 
homogeneous  cartilagd  which  forms  the  mould  of  the  bone, 
becomes  hollowed  out  so  as  to  present  irregular  cavities,* 
which  subsequently  form  canals  lined  by  a  vascular  membrane 
and  filled  with  a  viscous  fluid  "which  extend  to  the  centre  of 
its  structure.  One  of  these  canals  forms  subsequently  the 
nutritious  foramen.  The  cartilage  becomes  opaque  and 
yellowish  round  this  spot,  the  vessels  convey  red  blood, 
numerous  red  points  are  formed  in  the  structure,  and  ossification 
commences  at  the  centre  of  the  bone  ;  never  upon  the  surface. 
In  the  long  bones  a  bony  ring  is  first  formed  in  the  centre,  and 
the  vascular  canals  extend  themselves  in  the  direction  of  the 
extremities — in  the  flat  and  thick  bones,  in  radii,  attended  by  a 
redness  in  the  cartilage,  nearest  the  seat  of  ossification,  and  a 
diffused  yellowness  beyond  it.  From  these  canals  the  ossific 
material  is  deposited,  and  the  central  point  of  ossification 
grows,  till  the  bone  is  completed.  As  the  bony  portion 
advances  in  growth,  its  redness  diminishes,  and  the  vascular 
canals  which  are  at  first  la^e,  decrease  in  size,  so  as  to  become 
in  the  adult  bone  microscopical.  The  ossescent  or  provisional 
cartilage  of  the  bone,  is  solid  and  has  in  no  instance  any  cavity 
in  its  centre.  The  ring  of  bone  which,  as  before  observed,  is 
the  first  step  of  development  in  the  long  bones,  has  a  cavity 
in  its  centre  which  is  subsequently  destined  to  lodge  the 
medulla.  In  the  flat  bones,  and  especially  those  of  the  cranium, 
ossification  commences  between  the  second  and  third  months 
of  foetal  life.  Those  of  the  cranium  are  formed  between  the 
pericranium  and  dura  mater,  and  their  cartilaginous  mould  is 
so  thin  and  soft,  that  Howship  and  Beclard  have  denied  its 
existence.  The  vascularity  commences  in  them  at  a  central 

*  According  to  the  German  anatomists,  see  page  44,  the  hollowing  of  these 
canals,  is  produced  by  an  aggregation  of  the  cartilaginous  corpuscles  into  a  series 
of  linear  ranges,  between  which  the  vessels  shoot  that  convey  the  earthy  mate- 
rial of  the  bone. — p. 


GROWTH  OF   BONE.  43 

point,  and  the  ossificrays  pass  off  in  a  straight  direction,  as  seen 
in  Fig.  6,  page  41. 

— Many  of  these  bones,  as  well  as  of  those  in  other  parts  of 
the  body,  are  of  such  irregular  shape,  as  to  be  inca]>able  of 
being  formed  of  fibres  radiating  from  a  single  centre ;  they  are, 
therefore,  developed  from  several  centres,  the  rays  of  which 
finally  meet  and  inosculate.  The  development  of  the  thick 
bones,  and  the  epiphysis  of  the  long  bones,  take  place  in  accord- 
ance with  the  same  laws. 

— Growth  of  Bones.  In  all  the  long  bones,  the  extremities  or 
epiphyses,  are  developed  in  separate  pieces  and  between  them 
and  the  ossified  shaft  there  is  a  cartilaginous  lamen,  which  does 
not  disappear  till  the  bone  has  attained  its  full  development. 
The  bones  increase  in  length  by  the  continuous  deposit  of  new 
ossific  matter  in  this  lamen  of  cartilage,  which  seems  retained 
there  as  a  soft  bed  for  that  purpose.  As  soon  as  the  bone  has 
attained  its  full  length  at  puberty,  the  lamen  disappears,  and 
the  epiphysis  and  shaft  are  consolidated,  as  seen  in  Fig.  3,  where 
2  is  the  layer  of  the  cartilage,  beginning  to  disappear  at  one 
point.  The  long  bones  increase  in  diameter,  by  the  successive 
addition  of  new  bony  matter  between  the  periosteum  and  bone. 
It  is  said  to  be  deposited  from  the  periosteum  itself:  but  that 
opinion  is  incorrect,  for  no  membrane  can  form  a  tissue,  so 
much  at  variance  with  its  own  structure.  It  is  the  blood- 
vessels which  merely  ramify  minutely  through  the  periosteum, 
that  deposit  the  matter  upon  the  surface  of  the  bone,  precisely 
as  they  do  in  the  centre.  This  mode  of  growth  in  diameter  by 
concentric  circles,  has  been  proved  by  experiments  made  with 
mixing  madder  at  intervals  in  the  food  of  animals,  by  Duha- 
mil,*  Hunter,  Professors  Homer,  Mussey,  myself,  and  others. 
On  killing  the  animals,  red  rings  were  found  surrounding  the 
bones,  alternated  with  white  ones  corresponding  to  the  periods  of 

*  Duharail  who  was  no  anatomist,  considered  the  growth  of  bones,  as  analo- 
gous to  the  vegetation  of  plants.  He  placed  a  silver  ring  upon  the  bone  of  a 
young  animal,  which  he  afterwards  fed  interruptedly  on  madder.  The  white 
and  red  strata  alternately  covering  the  ring  as  he  found  on  killing  the  animal, 
he  erroneously  considered  not  deposited  on  the  outer  surface,  but  formed  by  the 
expansion  of  the  bone  bulging  over  it  as  takes  place  in  plants. — r. 


44  OSSEOUS  CORPUSCLES. 

administering  or  suspending  the  madder.*  At  the  same  time, 
that  there  is  this  increase  of  matter  on  the  surface,  there  is  a 
corresponding  enlargement  in  the  central  or  medullary  cavity, 
which  is  said  to  be  effected  by  the  action  of  the  absorbents. 
It  appears  to  me,  however,  to  be  far  more  likely  due  to  an 
interstitial  growth,  by  which  the  walls  of  the  cavity  are  in- 
creased in  dimensions  and  the  cavity  itself  necessarily  enlarged. 
—  Corpuscles.  Purkinje  has  -recently  Fig.  7.f 

discovered  in  cartilage  generally,  and 
especially  in  the  cartilage  of  bone,  round- 
ed corpuscles,  which  are  much  larger 
in  diameter  than  the  transverse  sections 
of  the  canals  described  in  p.  30.  The 
existence  of  these  corpuscles,  has  also 
been  confirmed  by  the  microscopical  re- 
searches of  Deutsch,  Miescher,  Sharpey 
and  others ;  according  to  Miescher  they 
correspond  with  the  brown  spots  described 
by  Lewenhoeck  as  his  second  order  of  foramina.  In  bone  de- 
prived of  its  earthy  parts  by  maceration  in  acid,  their  appear- 
ance is  that  of  small  brown  spots,{  pellucid  in  the  centre,  and 
surrounded  with  a  distinct  opaque  line,  which  by  a  high  magni- 
fying power,  appeared  to  Miescher  to  be  denticulated.  They 
are  situated  between  their  lamellae,  the  long  diameter  being  ob- 


*  Rutherford,  of  Edinburgh,  first  explained  this  coloring  of  the  bone,  without 
that  of  the  other  tissues,  by  the  affinity  of  the  madder  for  the  phosphate  of  litne, 
upon  which  it  acted  as  a  mordant. — p. 

f  Fig.  7,  is  a  representation  from  Miescher  of  the  progress  of  ossification, 
caused  by  inflammation  in  an  adult  bone,  which  takes  place  nearly  in  the  same 
manner  that  new  bone  is  formed  ;  a  a,  the  cartilage,  the  first  stage  in  the  forma- 
tion of  bone,  and  the  small  bodies  thickly  interspersed  through  it  are  the  carti- 
lage corpuscles  of  Purkinje  j  b  b,  the  first  or  primary  stage  of  the  bony  structure, 
in  which  the  osseous  corpuscles  arrange  themselves  somewhat  into  lines,  and 
the  bony  fibres  shoot  in  between  them,  and  in  the  thickness  of  the  corpuscles 
themselves  saline  particles  are  deposited,  which  renders  them  opaque  ;  c  c,  the 
new  structure  completely  ossified. 

$  These  as  shown  p.  46,  are  now  believed  to  be  new  bodies,  bony  corpuscles, 
which  supplant  the  cartilaginous  corpuscles  of  Purkinje.  The  above  account 
is  retained  in  order  to  show  progressively  the  history  of  the  discovery. 


NEW  VIEWS  OF  THE  GROWTH  OF  BONES.  45 

lique  in  regard  to  the  direction  of  the  lamellae,  and  when  the 
work  of  ossification  has  not  commenced,  appear  to  have  no  fixed 
arrangement,  and  are  wedge-shaped,  oval,  oblong,  or  flattened, 
see  Fig.  8.  Of  the  nature  of  these  corpuscles,  little  f  is  posi- 
tively known.  Neither  vegetable  or  mineral  acids  have  any 
effect  upon  them,  except  to  render  them  a  little  more  prominent 
on  the  surface  of  a  section  of  cartilage.  Alcohol,  ether,  or  a 
cold  solution  of  caustic  potash  does  not  change  them  ;  but  if 
exposed  to  a  hot  caustic  solution,  or  a  long  time  macerated  in 
water  they  become  completely  liquified. 

— The  size  of  the  corpuscles  according  to  the  measurements  of 
Miescher,  varied  in  length  from  the  0.0048  to  the  0.0072  parts 
of  a  line,  and  in  breadth  from  the  0.0017  to  the  0.0030.*  The 
researches  of  this  anatomist,  of  Miiller,  and  other  recent  ob- 
servers, have  shown  that  the  formation  of  cartilage  always 
precedes  that  of  bone,f  and  that  each  ossescent  or  temporary 
cartilage,  is  an  organic  tissue,  homogeneous,  more  or  less  pel- 
lucid, elastic,  in  its  first  state  almost  colorless,  afterwards  assum- 
ing a  bluish  cast,  and  having  a  great  many  peculiar  minute 
corpuscles  interspersed  through  its  substance,  as  shown  by  the 
microscope.  In  the  conversion  of  cartilage  into  bone,  the 
'change  first  commences  in  the  cartilage  that  surrounds  the 
corpuscles. 

— Weber,  Beclard  and  others,  believe  that  the  calcareous  matter 
is  deposited  by  the  vessels,  in  the  cartilaginous  mould  of  the 
•tyone,  as  a  foreign  body,  and  that  the  cartilaginous  particles  are 
removed  in  proportion  to  make  room  for  it ;  but  this  is  a  mere 
opinion  which  has  not  been  proven. 

— Miescher,  asserts  that  he  was  unable  even  with  the  micro- 
scope to  ascertain  in  what  manner,  the  calcareous  particles  were 

*  More  recent  researches  seem  to  prove  that  the  average  diameter  of  these 
cartilage  cells  or  corpuscles,  is  about  the  one  twelve  hundredth  or  one  fifteen 
hundredth  part  of  an  inch. — P. 

f  This  which  was  admitted  by  Albinus,  Haller/  Scarpa;  and  others,  has  been 
denied  by  Howship  and  Beclard,  in  regard  to  the  diaphysis  of  the  long  bones, 
and  the  bones  of  the  cranium.  In  the  bones  of  the  rabbit,  Miescher  found  a 
mould  of  cartilage  before  a  particle  of  ossific  matter  had  been  deposited,  and 
between  the  pericranium  and  dura  mater,  a  thin  stratum  of  cartilage.  An  ex- 
ception must  be  made  however  in  regard  to  certain  flat  bones  of  the  human 
skull,  as  the  parietal. — p. 


46 


NEW  VIEWS   OF  THE   GROWTH  OF  BONES. 


received   into  the  cartilage,  the  strongest  powers  of  the  micro- 
Fig.  8.*  scope   exhibiting  no  cells  in  which   they 

were  placed,  nor  any  calcareous  particles 
of  the  size  of  the  dispersed  corpuscles  ; 
all  that  appeared  positively  was  that  the 
cartilage  seemed  by  degrees  to  assume  the 
aspect  of  bone. 

The  more  recent  researches  of  Gerber,f 
have  given*  if  not  a  perfectly  clear,  at 
least  a  more  satisfactory  explanation  of 
the  manner  in  which  the  ossific  cartilage 
is  so  modified,  as  to  form  bone.  The 
primitive  physical  formation  of  all  car- 
tilage is  cellular,  that  is  they  grow  from 
cell-germs,  as  is  the  case  with  the  other 
tissues  of  the  body.  These  cell-germs  or 
cartilage  corpuscles  are  seen  at  A.  Fig.  8, 
magnified  250  diameters.  Between  these 
cells  and  filling  up  the  vacant  spaces 
between  them,  is  an  amorphous,  hyaline 
or  transparent  intercellular  substance ; 
the  cells  themselves  are  filled  with  .  a 
softish  granular  matter.  As  the  cartilage* 
increases  in  growth,  new  cells  are  develop- 
ed in  the  hyaline  substance  by  which  the 
older  ones  are  pushed  farther  and  farther 
from  each  other.  The  original  cells  pro-  * 
duce  two  or  more  young  or  secondary 
cells  by  the  development  of  their  gra- 
nular nuclei :  between  these  secondary 
cells  is  also  formed  a  secondary  hya- 
line substance,  and  thus  the  orginal  cells  form  each  one  a  little 
group  of  cells  enclosed  within  itself,  and  to  each  group  the  name 


*  Fig.  8.  A  scheme  intended  to  represent  cartilage  in  the  progressive  stages  of 
ossification,  magnified  250  diameters.  A.  Cartilage  with  the  regularly  dissemi- 
nated corpuscles  of  Purkinje — cellular  cartilage  B.  The  corpuscles  when  ossi- 
fication has  begun,  are  forced  into  groups,  between  which  the  hyaline  cartilage 
is  transformed  into  bone  cartilage.  This  bone  cartilage  has  now  undergone  a 
change,  so  as  to  be  chemically  different  from  those  cartilages  which  are  to  remain 

f  Elements  of  General  and  Minute  Anatomy  by  T.  Gerber.    London,  1842. 


NEW  VIEWS  OF  THE  GROWTH  OF  BONES.  47 

of  cartilage  corpuscle  is  still  applied.  This  is  the  common  em- 
bryonic constitution  of  cartilage.  The  fixed  character  of  the 
cartilage  depends  upon  the  after  changes  which  take  place  in 
it.  If  fibre-cartilage  be  formed,  the  intercellular  or  hyatme  sub- 
stance is  developed  in  the  form  of  fibres  and  the  cells  disappear 
altogether.  If  elastic  cartilage,  fibres  are  developed  around  the 
cells  forming  a  kind  of  network.  If  ossific  cartilage,  the  hya- 
line substance  takes  on  a  stratified  arrangement  round  the  car- 
tilage cells,  and  in  it  a  new  set  of  corpuscles  are  developed, 
called  the  bone  corpuscles,  that  are  the  nuclei  of  the  bone 
cells,  see  Fig.  9,  of  which  the  microscope  has  shown  in  reality 
all  bony  structure  to  consist.  As  this  process  is  commencing, 
the  cluster  of  cartilage  cells  called  cartilage  corpuscles,  become 
compressed  together.  The  secondary  hyaline  substance  becomes 
dissolved,  transudes  through  the  walls  of  the  parent  cell, 
coagulates  round  it,  and  in  this  state  of  cytoblastema  as  it  is 
called — this  basis  structure  for  the  growth  of  other  parts — it  con- 
stitutes the  proper  ossific  cartilage.  In  it  arise  the  bone  cor- 
puscles, called  cytoblastty  or  germs,  from  which  are  formed  the 
bone  cells.  These  follow  the  same  mode  of  development,  as 
the  embryonic  cartilage  cells :  that  is  new  corpuscles  are 
forming  in  the  cytoblastema,  while  those  recently  produced 
are  growing ;  the  cartilage  corpuscles  ever  more  closely  com- 
pressed together  disappear  ;  radiated  points,  nutrient  vessels,  etc. 
make  their  appearance,  the  nuclei  of  the  bone  cells,  (corpuscles,) 
and  the  cells  themselves  when  completely  formed  receive  depos- 
its of  calcareous  salts,  and  the  formation  of  bone  is  achieved. 

flexible  during  life.  It  does  not  on  boiling  yield  gelatine  like  them,  but  a  sub- 
stance called  chondrin,  which  differs  from  gelatine  in  not  being  precipitated  by 
tannic  acid,  etc.  C.  The  groups  of  cartilage  corpuscles  are  now  seen  completely 
inclosed  by  bone  cartilage.  D.  The  cartilage  corpuscles  are  here  rendered  less 
transparent  by  the  process  of  resolution  that  is  going  on  ;  the  bone  corpuscles 
are  at  the  same  time  making  their  appearance  in  the  bone  cartilage.  E.  The 
cartilage  corpuscles  are  dissolved  and  partially  removed.  F.  The  cartilage  cor- 
puscles have  disappeared  ;  have  been  absorbed.  G.  In  spongy  bones,  the  spaces 
occupied  by  the  cartilage  corpuscles  remain  as  cells  filled  with  globules  of  fat. 
In  compact  bones  the  cells  are  reduced  to  minute  canals,  by  the  growth  of  bony 
matter,  or  they  disappear  entirely.  In  Fig.  9,  there  is  a  representation  of  bone 
in  its  perfectly  formed  state,  magnified  450  diameters,  and  representing  the  bone 
cells  or  corpuscles,  with  iheir  calcareous  canals. 


48  FORMATION    OF    CALLUS. 

Fig.  9.*  It  is  according  to  this  from  a  peculiar  sub- 
stance, not  ordinary  cartilage,  that  bone  is  pro- 
duced, and  we  now  know  that  the  effused  fluid 
of  which  the  callus  in  fractures  is  formed,  is  in 
some  respects  different  from  the  cartilagi- 
nous mould  of  bone,  and  that  in  fact  bone 
is  developed  in  many  parts  of  the  body,  as 
in  the  human  .skull  for  instance,  without  the. 
existence  of  any  previous  cartilaginous  basis. 

Formation  of  Callus. 

— The  most  ancient  opinion  entertained  in  regard  to  the  mode  of 
union  between  broken  bones,  was,  that  it  was  owing  to  the  con- 
cretion of  a  viscous  fluid,  or  imaginary  osseous  juice  poured  out 
between  the  fragments.  This  was  the  opinion  of  Haller.  Du- 
hamil  demonstrated  the  fallacy  of  this  belief,  by  numerous 
experiments,  and  instituted  a  theory  of  his  own  which  is  much 
nearer  the  truth.  According  to  him  the  production  of  callus  or 
new  bony  matter,  is  owing  to  the  swelling,  elongation,  and 
subsequent  adhesion  between  the  periosteum  and  medullary 
membrane  of  one  fragment  with  the  corresponding  parts  of  the 
other;  and  that  from  these  membranes  thus  modified,  bony 
matter  was  deposited  in  the  form  of  a  ring  on  the  exterior  of 
the  bone  and  a  plug  in  its  medullary  cavity,  which  held  the 
fragments  together  by  passing  across  the  cavity  of  fracture,  and 
sometimes  by  prolongations  passing  between  them  through  the 
cavity.  John  Hunter  believed  that  the  re-union  of  fractured 
bones  took  place  from  the  organization  of  the  blood  effused 
around  the  fracture  and  between  the  fragments ;  a  doctrine 
which  now  has  few  supporters. 
— The  credit  of  giving  the  most  faithful  account  of  the  forma- 


*  Fig.  9.  Bone  corpuscles,  a,  magnified  450  diameters,  which  have  here  been 
converted  into  bone  cells,  b.  Branches  of  the  bony  cells  which  by  their  inoscu- 
lations form  a  net  work.  They  are  called  by  Mttller  the  canaliculi  calicophori. 
It  is  not  yet  fully  decided  whether  or  not  the  cells  and  their  branches  are  filled 
with  calcareous  matter,  or  merely  incrusted  with  it.  The  diameter  of  these 
calcigerous  canals  (canalic.  calicoph.)  is  reckoned  at  their  largest  parts  to  be 
between  one  fourteen  thousandth  and  the  one  twenty  thousandth  part  of  an  inch. 


RESTORATION  OF  FRACTURED  BONES.  49 

tion  of  callus,  is  due  to  Dupuytren*  and  Sanson.  According 
to  these,  the  union  of  fragments  of  bone,  is  effected  by  the  for- 
mation of  two  successive  stages  of  callus.  One  which  is  pro- 
visional or  temporary,  is  completed  usually  in  the  sp^ce  of 
thirty  or  forty  days,  by  the  union  and  ossification  of  the  perios- 
teum, cellular  tissue,  and  even  in  some  cases  of  the  muscles, 
so  as  to  constitute  an  external  ring — and  of  the  medullary  mem- 
brane, so  as  to  constitute  an  internal  plug.  The  other,  which 
he  calls  final  or  permanent,  is  formed  by  the  re-union  of 
the  surfaces  of  the  fracture,  with  a  solidity  so  much  superior  ./ /C 
to  that  of  the  bone  in  other  parts,  that  it  will  break  any  where 
again,  rather  than  at  that  point,  and  which  is  never  fully  com- 
pleted, notwithstanding  the  limb  appears  earlier  than  this  restored 
to  its  proper  uses,  under  eight,  ten,  or  twelve  months,  by  which 
time  all  the  provisional  callus  has  been  removed,  and  the  medul- 
lary canal  is  completely  re-established. 

— Dupuytren  divides  the  successive  organic  changes,  which 
attend  the  formation  of  callus,  into  five  periods. 
— The  first  period,  extends  from  the  time  of  the  fracture  to  X 
the  eighth  or  tenth  day,  and  is  characterized  by  the  following 
phenomena  :  the  medullary  membrane,  the  medulla,  the  perios- 
teum, cellular  tissue,  and  sometimes  the  muscles  themselves,  are 
torn  at  the  time  the  fracture  takes  place  ;  blood  escapes  from 
the  ruptured  vessels,  surrounds  the  fragments,  spreads  in  the 
medullary  canal  and  infiltrates  in  the  surrounding  tissue  :  the 
hemorrhage  stops ;  a  slight  inflammation  is  developed  in  all 
these  parts,  which  is  the  first  step  towards  the  production  of 
the  callus.  The  cellular  tissue  surrounding  the  bone,  becomes 
very  vascular,  is  thickened,  loses  its  elasticity,  and  acquires  a 
great  degree  of  consistence ;  it  sends  irregular  processes  into 
the  neighboring  muscles,  transforms  them  to  a  greater  or  less 
extent  into  an  analogous  tissue,  and  unites  them  in  a  common 
structure  with  the  periosteum,  which  is  also  much  thickened 
and  very  vascular.  A  nearly  similar  change  takes  place  in  the 
cavity  of  the  bone  in  respect  to  the  medulla  and  its  membrane. 
The  calibre  of  the  medullary  canal  is  contracted  by  the  thickening 

-   *  Journal  Univ.  de  Med.  torn.  20. 
5 


50  RESTORATION  OF  FRACTURED  BONES. 

of  the  membrane,  which  presents  a  fleshy  appearance,  in  con- 
sequence of  a  sort  of  gelatinous  infiltration.  The  effused  blood 
becomes  absorbed,  and  a  ropy,  viscous,  gelatinous  fluid,  is 
poured  out  between  the  ends  of  the  fragments,  which  is  essential 
to  the  production  of  the  permanent  callus. 

— The  second  period  extends  from  the  tenth  or  twelfth,  to  the 
twentieth  or  twenty-fifth  day.  During  this  period,  the  engorge- 
ment of  the  surrounding  parts,  diminishes  and  the  muscles  are 
liberated  :  but  the  cellular  tissue  remains  condensed  and  con- 
centrated round  the  fracture,  presenting  grooves  or  even  canals 
to  the  tendons  of  the  muscles  if  any  pass  in  the  vicinity  of  the 
fracture,  in  which  they  are  able  to  play,  though  with  little  free- 
dom, in  consequence  of  some  existing  induration  of  the  cellular 
tissue.  This  constitutes  the  provisional  callus,  the  external 
portion  of  which  is  thickest  at  the  place  of  fracture,  and  insensibly 
terminates  upon  the  fragments  of  bone.  Its  internal  portion  is 
formed  by  the  periosteum,  which  is  closely  attached  to  the  bone. 
Its  structure  is  whitish,  homogeneous,  and  of  a  cartilaginous  or 
fibro-cartilaginous  character.  The  medullary  membrane  forms  a 
similar  plug  of  provisional  cartilaginous  matter,  which  fills  up  the 
whole  cavity  of  the  bone,  above  and  below  the  place  of  fracture. 
The  viscous  or  gelatinous  fluid  interposed  between  the  ends  of 
the  bones,  is  now  rose-colored  or  red,  presents  sometimes  a  floc- 
culent  appearance,  and  is  adherent  by  its  margins  to  the  external 
and  internal  callus.  The  limb  may  still  be  bent  at  the  place  of 
fracture,  but  no  crepitation  can  be  produced. 
— The  third  period  extends  from  the  twentieth  or  twenty-fifth 
day,  to  the  thirtieth,  fortieth  or  sixtieth,  according  to  the  age 
and  health  of  the  patient. 

— Ossification  commences  in  the  centre  of  the  cartilage,  and  by 
degrees  the  whole  tumor,  internal  and  external,  becomes  os- 
seous. It  is  very  vascular,  and  Howship*  has  succeeded  in 
injecting  the  vessels.  If  at  this  period  the  bone  be  cut  longitu- 
dinally, the  provisional  callus  will  be  found  presenting  all  the 
characters  of  spongy  bone,  while  the  fragments  will  be  found 

*  Microscop.  Observ. 


TERMS  USED  IN  THE  DESCRIPTION  OF  BONES  AND  JOINTS.    51 

movable  upon  each  other,  the  substance  poured  out  between 
them,  not  having  apparently  undergone  much  change. 
— The  fourth  period  extends  from  the  fiftieth  or  sixtieth  day, 
to  the  fifth  or  sixth  month.  During  this  period  the  ^callus 
has  been  changed  from  the  state  of  spongy,  to  that  of  compact 
bone. 

— The  substance  intermediate  to  the  fragments,  which  present- 
ed itself  under  the  form  of  a  line  or  septum  between  them, 
becomes  more  consistent,  presents  a  whiter  hue,  and  is  ossified 
towards  the  end  of  this  period ;  and  the  permanent  callus  is 
now  completed. 

— The  fifth  period  extends  from  the  fifth  or  sixth,  to  the 
eighth,  tenth  or  twelfth  month,  during  which  time  the  whole 
of  the  provisional  callus  is  entirely  removed,  the  object  of  its 
formation  having  been  effected,  that  of,  securely  holding  the 
bones  together  like  splints  till  the  fractured  surfaces  become 
firmly  reunited.  The  periosteum  resumes  its  usual  thickness 
and  polish,  and  the  muscles  and  tendons  their  entire  freedom  of 
motion. 

— The  internal  plug  of  callus  having  been  removed  by  absorp- 
tion, the  central  cavity  of  the  bone,  the  medullary  membrane 
and  the  marrow  itself,  present  their  usual  appearance. — 

i 

Of  the  Terms  used  in  the  Description  of  Bones  and  their 
Articulations. 

The  study  of  this  subject  has  been  rendered  more  difficult 
by  the  unnecessary  introduction  of  many  hard  words,  but  some 
of  these  words  are  so  generally  used,  that  they  ought  to  be 
understood  by  the  student  of  anatomy. 

The  word  process  signifies  any  protuberance  or  eminence 
arising  from  a  bone. 

Particular  processes  receive  names  from  their  supposed  resem- 
blance to  certain  objects  ;  and  their  names  are  very  often  com- 
posed of  two  Greek  words  ;  thus  the  term  coracoid,  which  is 
applied  to  a  well-known  process,  is  derived  from  the  Greek 
words  xo£«!,,  a  crow,  and  eidos*,  resemblance. 


52    TERMS  USED  IN  THE  DESCRIPTION  OF  BONES  AND  JOINTS. 

If  a  process  has  a  spherical  form,  it  is  called  a  head.  If  the 
head  is  flattened  on  the  sides,  it  is  denominated  a  condyle. 

A  rough  protuberance  is  called  a  tuberosity.  ,A  ridge  on  the 
surface  of  a  bone  is  called  a  spine. 

The  term  apophysis,  is  nearly  synonymous  with  process.  It 
signifies  a  protuberance  that  has  grown  out  of  the  bone,  and  is 
used  in  opposition  to  the  term  epiphysis,  which  signifies  a  por- 
tion of  bone  growing  upon  anther,  but  distinct  and  separable 
from  it ;  as  is  the  case  in  infancy  with  the  extremities  of  the 
long  bones. 

The  cavities  on  the  surfaces  of  bones  are  named  in  the  same 
way,  as  will  appear  by  a  reference  to  the  glossary  at  the  end  of 
this  work. 

Words  of  this  kind  have  been  used  most  profusely  in  the 
descriptions  of  articulations,  and  here  also  their  utility  is  doubt- 
ful. Therefore,  for  many  terms  used  on  this  occasion,  the  reader 
is  referred  to  the  glossary  ;  but  the  following  are  necessary  to 
be  understood. 

SYMPHYSIS  does  not  merely  imply  the  concretion  of  bones 
originally  separate,  as  its  derivation  imports ;  but  it  is  under- 
stood also  to  mean  the  connexion  of  bones  by  intermediate 
substances.  Thus,  there  are  three  species  of  symphysis, 
particularly  noticed,  viz. 

Synchondrosis,  when  bones  are  connected  to  each  other  by 
cartilage  ;  as  the  ribs  and  sternum. 

Synneurosis,  when  they  are  connected  by  ligaments,  as  in  the 
movable  articulations. 

Syssarcosis,  when  they  are  connected  by  muscle.  The  different 
articulations  are  of  two  kinds,  viz.  Synarthrosis  and  Diar- 
throsis. 

SYNARTHROSIS  is  the  name  of  that  kind  of  articulation  which 
does  not  admit  of  motion.  There  are  three  species  of  synar- 
throsis,  viz. 

Suture,  when  the  indented  edges  of  the  two  bones  are  received 
into  each  other,  as  is  the  case  with  the  bones  of  the  cra- 
nium. 


TERMS  USED  IN  THE  DESCRIPTION  OF  BONES  AND  JOINTS.    53 

Gomphosis,  when  one  bone  is  fixed  in  another  like  a  nail  in  a 

board,  as  the  teeth  in  their  sockets. 
Shindyksis,  when  the  thin  edge  of  one  bone  is  received  into  a 

narrow  furrow  of  another,  as  the  nasal  plate  of  the  efnmoid 

in  the  vomer. 
DIARTHROSIS  is  the   name  of  that  kind  of  articulation  which 

admits  of  motion.      Of  these  articulations    there   are    three 

species,  viz. 
Enarthrosis,  when  a  large  head  is  received  in  a  deep  cavity,  as 

the  head  of  the  thigh  bone  in  the  acetabulum. 
A.rthrodia,   when    the  head    is   connected   with    a    superficial 

cavity. 
GingKmus,  when  the  extremities  of  bones  apply  to  each  other 

so  as  to  form  a  hinge. 

But  most  of  the  important  joints  have  so  many  peculiarities 
that  they  cannot  be  understood  without  studying  them  sepa- 
rately. It  may,  therefore,  be  doubted  whether  the  classification 
and  arrangement  of  joints  is  any  way  necessary. 
— Some  of  the  more  common  anatomical  terms  are  explained 
in  this  place  and  in  the  glossary  ;  but  they  have  now  become 
too  numerous,  in  consequence  of  the  introduction  of  a  multitude 
of  new  ones,  some  of  which  are  of  foreign  origin,  to  be  sepa- 
rately defined  in  this  work.  A  medrcal  dictionary  will  better 
serve  the  purposes  of  the  student.  That  of  Prof.  Dunglison,* 
will  be  found  the  most  comprehensive  and  useful. 

*  Medical  Lexicon — A  new  Diet,  of  Med.  Science.  3d  edit,  by  Robley  Dun- 
glison,  M.  D.?  Prof.  Inst.  Med.,  tec.,  in  Jeff.  Med.  Coll.  Lea  &  Blanchard. 
Phil.  1842. 

5* 


54  OF    THE    HEAD. 


CHAPTER   II. 

Of  the  skeleton  and  its  different  parts,  and  the  individual  bones  of  which  they 

are  composed. 
• 

THE  bones  of  an  animal  arranged  and  connected  to  each  other 
in  their  natural  order,  separate  from  the  soft  parts,  compose  a 
skeleton. 

The  skeleton  is  said  to  be  natural  when  the  bones  are 
connected  by  their  own  ligaments,  which  have  been  allowed  to 
remain  for  that  purpose. 

It  is  called  artificial  when  the  bones  are  connected  with  wire, 
or  any  foreign  substance. 

The  artificial  skeleton  is  best  calculated  for  studying  the 
motions  of  the  different  bones,  because  the  dry  and  hard 
ligaments  of  the  natural  skeleton  do  not  allow  the  bones  to 
move ;  but  the  bones  of  young  animals  do  not  admit  of  the 
preparation  necessary  for  an  artificial  skeleton,  as  their  epiphyses 
would  separate,  and  they  are  therefore  formed  into  natural 
skeletons. 

The  study  of  the  skeleton  and  its  mechanical  properties,  as  a 
piece  of  machinery,  is  absolutely  necessary  to  a  perfect  under- 
standing of  many  motions  of  the  body,  and  of  the  action  and 
co-operation  of  muscles ;  but  any  observations  on  this  subject 
will  be  better  understood  after  the  individual  bones  and  the 
muscles  have  been  described. 

The  skeleton  is  divided  into  the  head,  the  trunk,  the  superior 
and  the  inferior  extremities. 

Of  the  Head. 

The  Head  comprehends  the  CRANIUM,  and  FACE. 

The  cranium  consists  .of  eight  distinct  bones,  which,  when 
placed  in  their  natural  order,  form  a  large  spheroidal  cavity  for 
containing  the  brain,  with  many  foramina  or  apertures  that 
communicate  with  it. 


OF    THE    CRANIUM.  55 

These  bones  are  of  a  flattened  form.  They  are  composed  of 
two  lamina  or  plates  called  tables,  with  a  cellular  structure 
between  them,  called  meditullium,  or  diploe.  The  external 
table  is  more  firm  and  thick  than  the  internal.  The  letter  is 
comparatively  very  brittle,  whence  it  is  called  the  vitreous 
table.  [Between  the  two  tables  which  compose  the  flat  bones 
of  the  cranium  and  running  through  the  diploe  are  several 
sinuses,  which  are  occupied  by  veins  in  the  recent  subject. 
They  were  discovered  by  M.  Fleury  about  forty  years  ago, 
while  he  was  Prosector  at  the  School  of  Medicine  in  Paris,  and 
engaged  in  some  inquiries  relative  to  the  structure  of  the 
cranium  at  the  instigation  of  M.  Chaussier.  The  account 
which  M.  Chaussier  gives  of  these  veins  is  as  follows :  they  are 
situated  in  the  middle  of  the  diploe  between  the  two  tables  of 
the  skull,  and  like  all  other  veins  are  intended  to  return  the 
blood  to  the  heart.  They  are  furnished  with  small  valves, 
have  extremely  thin  and  delicate  parietes,  and  commence  by 
capillary  rami6cations  coming  from  the  different  points  of  the 
vascular  membrane  which  lines  the  cells  of  the  diploe.  Their 
roots  are  at  first  extremely  fine  and  numerous,  form  by  their 
frequent  anastomoses  a  kind  of  network,  and  produce  by  their 
successive  junction,  ramuscles,  branches,  and  large  trunks, 
which,  becoming  still  more  voluminous,  are  directed  towards  the 
base  of  the  cranium.  Some  varieties  exist  in  regard  to  the 
number,  size,  and  disposition  of  these  trunks,  but  generally  one 
or  two  of  them  are  found  in  each  side  of  the  frontal  bone,  two 
in  the  parietal  bone,  and  one  in  each  side  of  the  qccipital 
bone.  Anastomoses  exist  between  these  several  trunks,  by 
which  the  veins  in  the  parietal  bone  are  joined  to  those  in  the 
frontal  and  in  the  occipital.  Branches  from  the  right  side  of 
the  head  also  anastomose  with  some  from  the  left  side.  Besides 
the  branches  already  mentioned,  one  or  two  smaller  than  the 
others  are  directed  towards  the  top  of  the  head  and  terminate  in 
the  longitudinal  sinus. 

The  descending  veins  of  the  diploe  communicate  in  their 
passages  with  the  contiguous  superficial  veins,  and  empty  into 
them  the  blood  which  they  receive  from  the  several  points  of 


56 


OF    THE    CRANIUM. 


the  diploe.  These  communications  are  produced  through 
small  foramina  which  penetrate  from  the  surface  of  the  bone 
to  the  diploe.  The  trunks  of  such  diploic  veins  as  are  continued 
to  the  base  of  the  cranium,  open  partly  into  sinuses  of  the  dura 
mater,  and  partly  into  the  venous  plexus  at  the  base  of  the 
pterygoid  apophyses,  and  form  there  the  venous  communications 
called  the  emissaries  of  Santorini.  Moreover,  there  are 
communications  sent  from  the  dtploic  veins  through  the  porosi- 
ties of  the  internal  table  of  the  skull  to  the  veins  of  the  dura 
mater.  This  fact  is  rendered  very  evident  by  tearing  off  the 
skull  cap,  when  the  surface  of  the  dura  mater  will  be  studded 
with  dots  of  blood,  and  the  internal  face  of  the  bone  also, 
particularly  in  apoplectic  subjects.  It  appears  indeed  that  the 
arteries  of  the  cranium  are  principally  distributed  on  its  external 
surface,  and  the  veins  on  its  internal  surface  and  diploe. 

In  the  infant  the  diploic  veins  are  small,  straight,  and  have 
but  few  branches  :  in  the  adult  they  correspond  with  the 
description  just  given  ;  and  in  old  age  they  are  still  more  con- 
siderable, forming  nodes  and  seeming  varicose.  In  children, 
when  the  bones  are  diseased,  they  partake  of  the  latter 
character.  In  order  to  see  them  fully,  the  external  table  of  the 
skull  must  be  removed  with  the  chisel  and  mallet,  both  from  its 
vaults  and  base.]* 

The  periosteum,  which  is  on  their  external  surface,  is  called 
pericranium.  Internally  the  dura  mater,  or  membrane  which 
covers  the  brain,  supplies  the  place  of  periosteum. 

There  are  eight  of  these  bones,  which  are  thus  denominated : 
Os  Frontis,  Ossa  Parietalia,  Ossa  Temporum,  Os  Occipitis, 
Os  Sphenoides,  and  Os  Ethmoides.  The  two  last  are  called 
common  bones,  to  denote  that  they  are  connected  with  the  bones 
of  the  face  as  well  as  with  those  of  the  cranium. 

The  os  frontis  forms  the  whole  fore  part  of  the  vault  of  the 

*  The  diploe,  or  meditullium,  corresponds  exactly  in  structure  and  situation 
with  the  spongy,  or  cellular  tissue  of  the  other  bones  of  the  body,  though  it  has 
unnecessarily  received  a  distinct  name.  Neither  are  the  diploic  sinuses  peculiar 
to  the  bones  of  the  skull.  They  are  found  presenting  exactly  the  same  appear- 
ance in  the  bodies  of  the  vertebrae,  and  appear  in  fact  to  be  but  a  development 
of  the  canaliculated  tissue  of  the  oiher  bones.  See  Fig.  5,  page  30. — P. 


THE    SUTURES.  57 

cranium  :  the  two  ossa  parietalia  form  the  upper  and  middle 
part  of  it ;  the  ossa  temporum  compose  the  lower  part  of  the 
sides ;  the  os  occipitis  makes  the  whole  hinder  part  and  some 
of  the  base;  the  os  ethmoides  is  placed  between  the  ambits  of 
the  eyes,  and  the  sphenoides  extends  across  the  base  of  the 
cranium. 
i 

The  Sutures,  f- 

The  above  bones  are  joined  to  each  other  by  five  sutures  ;  the 
names  of  which  are  the  Coronal,  Lambdoidal,'  Sagittal,  and 
two  Squamous. 

The  coronal  suture  is  extended  over  the  head,  from  within 
about  an  inch  of  the  external  angle  of  one  eye,  to  the  like  dis- 
tance from  the  other ;  which  being  near  the  place  where  the 
ancients  wore  their  garlands,  this  suture  has  hence  got  its 
name.  Though  the  indentations  of  this  suture  are  conspicuous 
in  its  upper  part,  yet  an  inch  or  more  of  its  end  on  each  side 
has  none,  but  is  squarnous  and  smooth. 

The  lambdoidal  suture  begins  some  way  below,  and  further 
back  than  the  vertex  or  crown  of  the  head,  whence  its  two  legs 
are  stretched  obliquely  downwards,  and  to  each  side,  in  form 
of  the  Greek  letter  A?  and  are  now  generally  said  to  extend 
themselves  to  the  base  of  the  skull ;  but  formerly,  anatomists 
reckoned  the  proper  lambdoidal  suture  to  terminate  at  the 
squamous  sutures :  and  the  portion  continued  from  them  on  each 
side,  where  the  indentations  are  less  conspicuous  than  in  the 
upper  part  of  the  suture,  they  called  additamentum  suturae 
lambdoidis. 

This  suture  is  sometimes  very  irregular,  being  made  up  of  a 
great  many  small  sutures,  which  surround  a  number  of  insulated 
bones,  that  are  generally  more  conspicuous  on  the  external 
surface  of  the  skull  than  internally.  These  bones  are  commonly 
called  triquetra  or  wormiana ;  their  formation  is  owing  to  a 
greater  than  ordinary  number  of  points  of  ossification  in  the 
skull,  or  to  the  ordinary  bones  of  the  cranium  not  extending 
their  ossification  far  enough  or  soon  enough ;  in  which  case, 
the  unossified  interstice  between  such  bones  begins  a  separate 


58  THE    SUTURES. 

ossification,  in  one  or  more  points ;  from  which  the  ossification 
is  extended  to  form  as  many  distinct  bones  as  there  were  points 
which  are  extended  into  the  large  ordinary  bones,  and  into 
each  other.* 

The  sagittal  suture  is  placed  longitudinally,  in  the  middle 
of  the  upper  part  of  the  skull,  and  commonly  terminates  at 
the  middle  of  the  coronal  and  of  the  lambdoidal  sutures ; 
between  which  it  is  said  to  be.placed,  as  an  arrow  is  between 
the  string  and  the  bow.  This  suture  is  sometimes  continued 
through  the  middle  of  the  os  fronds  down  to  the  root  of  the 
nose.  * 

The  squamous  agglutinations,  or  false  sutures,  are  one  on 
each  side,  a  little  above  the  ear,  of  a  semicircular  figure,  formed 
by  the  overlapping  (like  one  scale  upon  another)  of  the  upper 
part  of  the  temporal  bones  on  the  lower  part  of  the  parietal, 
where,  in  both  bones,  there  are  a  great  many  small  risings,  and 
furrows  which  are  indented  into  each  other :  though  these 
inequalities  do  not  appear  until  the  bones  are  separated.  In 
some  skulls,  indeed,  the  indentations  here  are  as  conspicuous 
externally  as  in  other  sutures ;  and  what  is  commonly  called 
the  posterior  part  of  this  squamous  suture,  always  has  the 
evident  serrated  form  ;  and  therefore  is  reckoned  by  some  a 
distinct  suture,  under  the  name  of  additamentum  posterius 
suturae  squamosae. 

The  squamous  suture  is  not  confined  to  the  conjunction  of 
the  temporal  and  parietal  bones,  but  is  made  use  of  to  join  all 
the  edges  of  the  bones  on  which  each  temporal  muscle  is 
placed  ;  for  the  two  parts  of  the.sphenoidal  suture,  which  are 
continued  from  the  anterior  end  of  the  common  squamous 
suture  just  now  described,  one  of  which  runs  perpendicularly 
downwards,  and  the  other  horizontally  forwards ;  and  also  the 
lower  part  of  the  coronal  suture  already  taken  notice  of,  may  all 
be  justly  said  to  pertain  to  the  squamous  suture. 

*  These  ossa  triquetra  or  wormiana  are  also  frequently  met  with  in  the  sagittal 
suture,  and  occasionally  in  all  the  different  sutures  of  the  cranium.  As  many 
as  fifteen  or  twenty  have  been  seen  in  a  single  head,  though  usually  their  num- 
ber is  much  less.  Where  the  cranium  is  of  a  globular  form,  few,  and  frequently 
none,  are  met  with.  They  never  begin  to  ossify  till  six  months  or  a  year  after 
birth.— P. 


THE    SUTURES.  59 

This  structure  appears  to  depend  upon  the  pressure  of  the 
temporal  muscle  externally,  and  the  resistance  of  the  brain 
within,  which  makes  the  bones  so  thin,  that  their  edges  opposed 
to  each  other  are  not  sufficiently  thick  to  stop  the  extetysion  of 
their  fibres  in  length,  and  thus  to  cause  the  common  serrated 
appearances  of  sutures ;  but  the  narrow  edge  of  the  one  bone 
slides  over  the  other.  The  squamous  form  is  also  more  con- 
venient here  ;  because  such  thin  edges  of  bones,  when  accurately 
applied  one  to  another,  have  scarce  any  rough  surface  to 
obstruct  or  hurt  the  muscle  in  its  contraction ;  which  is  still 
farther  provided  for,  by  the  manner  of  laying  these  edges  on 
each  other  ;  for,  in  viewing  their  outside,  we  see  the  temporal 
bones  covering  the  sphenoidal  and  parietal,  and  this  last  sup- 
porting the  sphenoidal,  while  both  mount  on  the  frontal ;  from 
which  disposition  it  is  evident,  that  while  the  temporal  muscle 
is  contracting,  which  is  the  only  time  it  presses  strongly  in  its 
motion  on  the  bones,  its  fibres  slide  easily  over  the  external 
edges.  Another  advantage  of  this  structure  is,  that  the  whole 
part  is  made  stronger  by  the  bones  thus  supporting  each  other. 

The  indentation  of  the  sutures  are  not  so  strongly  marked 
on  the  inside  as  on  the  outside  of  the  cranium ;  and  sometimes 
the  bones  seem  to  be  joined  by  a  straight  line :  in  some 
skulls,  the  internal  surface  is  found  entire,  while  the  sutures 
are  manifest  without.  By  this  mechanism,  there  is  no  risk  of 
the  sharp  points  of  the  bones  growing  inwards,  since  the 
external  serrae  of  each  of  the  conjoined  bones  rest  upon  the 
internal  smooth-edged  table  of  the  other. 

The  advantages  of  the  sutures  are  these:  1.  The  cranium  is 
more  easily  formed  and  extended  into  a  spherical  figure,  than 
if  it  had  been  one  continued  bone.  2.  The  bones  which  are  at 
some  distance  from  each  other  at  birth,  may  then  yield,  and 
allow  to  the  head  a  change  of  shape,  accommodated  to  the 
passage  it  is  engaged  in.  Whence,  in  difficult  parturition, 
the  bones  of  the  cranium,  instead  of  being  only  brought 
into  contact,  are  sometimes  made  to  mount  one  upon  the 
other. 

[The   sutures   which  unite   the   bones  of  the   cranium,  are 


60  THE    SUTURES. 

generally  said  to  be  made  by  the  radii  of  ossification,  from  the 
opposite  bones  meeting  and  passing  each  other,  so  as  to  form 
a  serrated  edge.  This  explanation  is  however  insufficient,  for 
the  following  reasons :  we  always  find  the  sutures  in  the  same 
relative  situation,  and  observing  the  same  course  in  the  cranium ; 
if  they,  then,  depended  exclusively  on  so  mechanical  a  process, 
as  the  shooting  of  the  rays  of  bone  across  each  other  when  they 
met,  in  ossification  on  one  side^rf  the  head  occurring  sooner  or 
faster  than  on  the  other,  we  ought  to  find  the  sagittal  suture  to 
one  side  of  the  middle  line ;  it  should  also,  in  many  instances, 
be  found  crooked.  Moreover,  in  all  cases  where  bones  arise 
from  different  points  of  ossification  and  meet,  particularly  in 
the  flat  bones,  the  serrated  edges  ought  to  be  formed  ;  this, 
however,  is  not  the  case.  The  os  occipitis,  which  is  formed 
originally  from  four  points  of  ossification,  and  has  therefore  as 
many  bones  composing  it  in  early  life,  never  joins  these  bones 
together  by  the  serrated  edge ;  the  acromion  process  of  the 
scapula  is  never  united  to  its  spine  by  sutures ;  the  three  bones 
of  the  sternum  never  unite  by  suture,  and  the  same  observa- 
tion holds  good  in  many  other  instances.  Bichat,  who  rejects 
this  mechanical  doctrine,  advances  an  opinion  much  better 
founded.  The  dura  mater  and  the  pericranium,  before  ossifi- 
cation commences,  form  one  membrane,  consisting  of  two 
lamina  ;  it  is  generally  known  that  the  flat  bones  of  the 
cranium  are  secreted  between  these  two  lamina ;  now  the  out- 
line of  each  bone,  long  before  it  has  reached  its  utmost  limits, 
is  marked  off  by  partitions  passing  between  these  two  mem- 
branes. The  peculiar  shape  of  the  bony  junction,  or  the  suture 
in  adult  life,  will,  therefore,  depend  upon  the  original  shape 
of  the  partitions:  when  the  latter  are  serrated,  the  points  of 
ossification  will  fill  up  these  serrae ;  but  when  they  are  simply 
oblique,  the  squamous  suture  will  be  formed.  This  also 
accounts  for  cases  where  the  mode  of  junction  is  intermediate 
to  the  squamous  and  serrated  suture  ;  for  the  formation  of  the 
ossa  triquetra,  and  why  in  some  skulls  they  do  not  exist, 
whereas  in  others  their  extent  and  number  are  very  considera- 
ble. The  inference  will  also  be  drawn  from  this,  that  in  all  ossi- 


OS    FRONTIS. 


61 


fications  from  different  nuclei,  where  these  original  mem- 
braneous septa  do  not  exist,  a  suture  will  not  be  formed  ;  but 
the  bones  will  join  each  other,  as  in  a  case  of  callus  between 
the  broken  extremities  of  bones.  When  these  septa  "become 
weak  or  thin,  either  from  original  tendency,  as  in  the  case  of 
the  sagittal  suture,  which  in  early  life  is  continued  to  the  root 
of  the  nose  frequently  ;  or  from  advanced  age,  as  in  the  case 
of  nearly  all  sutures,  the  bones  of  the  opposite  sides  amalga- 
mate, and  no  appearance  of  suture  is  left.  It  is  easy  to  make  a 
preparation  illustrative  of  these  facts,  and  one  now  exists  in 
the  museum  of  the  University  of  Pennsylvania,  in  which,  by 
removing  the  bone  from  between  the  membranes  by  means  of 
an  acid,  and  afterwards  rendering  the  membranes  transparent 
with  oil  of  turpentine,  the  septa  are  seen  sufficiently  distinctly.] 

Os  Frontis. 

The  os  fronds,  as  its  name  imports,  forms  the  front  part  of 
the  cranium,  and  the  upper  portion  of  the  orbits  of  the  eyes. 

Fig.  10.*  The  external  surface  of  this 

bone  is  smooth  at  its  upper 
convex  part ;  but  several  pro- 
cesses and  cavities  are  ob- 
servable below ;  for  at  the 
angles  of  each  orbit,  the 
bone  projects  to  form  four 
processes,  two  internal,  and 
as  many  external  ;  which  are 
denominated  angular.  Be- 
tween the  internal  and  exter- 
nal angular  processes  on  each 
side,  an  arched  ridge  is  ex- 

*  The  external  surface  of  the  os  frontis.  1.  Frontal  protuberance  or  boss  of 
the  right  side.  2.  The  superciliary  ridge.  3.  Supra-orbital  ridge.  4.  External 
angular  process.  5.  Internal  angular  process.  6.  Supra-orbital  notch  for  the 
transmission  of  the  supra-orbital  nerve  and  artery  ;  it  is  occasionally  converted 
into  a  foramen.  7.  The  nasal  or  superciliary  boss ;  the  swelling  around  this 
point  denotes  the  situation  of  the  frontal  sinuses.  8.  The  temporal  ridge,  com- 
mencing from  the  external  angular  process  (4).  The  depression  in  which  fig. 
8  is  situated  is  a  part  of  the  temporal  fossa.  9.  The  nasal  spine. 

6 


62  OS   FRONTIS. 

tended,  on  which  the  eyebrows  are  placed.  Very  little  above 
the  internal  end  of  each  of  these  superciliary  ridges,  a  protuber- 
ance may  be  remarked  in  most  skulls,  called  the  superciliary  or 
nasal  boss,  where  there  are  large  cavities  within  the  bone,  called 
sinuses.  Between  the  internal  angular  processes,  and  in  front 
of  the  vacuity  for  the  ethmoid  bone,  the  edge  of  the  os  frontis 
is  serrated  for  articulation  with  the  ossa  nasi,  and  the  process 
of  the  upper  maxillary  bone  ;  a«d  from  the  centre  of  this  sur- 
face a  small  process  arises,  which  is  called  the  nasal  spine. 
From  the  under  part  of  the  superciliary  ridges,  the  frontal  bone 
runs  a  great  way  backwards  :  these  parts  are  called  orbitar 
processes,  which,  contrary  to  the  rest  of  this  bone,  are  concave 
externally,  for  receiving  the  globes  of  the  eyes,  with  their 
muscles,  fat,  &c. 

In  each  of  the  orbitar  processes,  at  the  upper  and  outer 
portion  of  the  orbit,  a  considerable  sinuosity  is  observed,  where 
the  glandula  lachrymalis  is  lodged.  Near  each  internal  angular 
process  a  small  pit  may  be  remarked,  where  the  cartilaginous 
pulley  of  the  superior  oblique  muscle  of  the  eye  is  fixed. 
Between  the  two  orbitar  processes,  there  is  a  large  vacuity 
which  the  cribriform  part  of  the  os  ethmoides  occupies.  The 
frontal  bone  has  frequently  little  caverns  formed  in  it  where  it  is 
joined  to  the  ethmoid  bone. 

The  foramina,  or  holes,  observable  on  the  external  surface  of 
the  frontal  bone,  are'three  in  each  side. 

On  each  supra-orbital  ridge,  3  fig.  10,  at  the  distance  of  one- 
third  of  its  length  from  the  nose,  is  a  foramen,  or  a  notch, 
through  which  pass  a  branch  of  the  ophthalmic  artery  and  a 
small  nerve  called  the  supra-orbital. 

In  the  internal  edge  of  each  orbitar  process  are  two  other 
foramina  denominated  anterior  and  posterior  orbitar,  or  eth- 
moidal  foramina,  which  lead  to  the  nose :  sometimes  they  are 
only  notches  or  grooves  which  join  with  similar  grooves  in  the 
bones  below,  and  form  foramina.  They  transmit  the  anterior 
and  posterior  ethmoidal  arteries  and  veins,  and  the  former  trans- 
mits likewise  the  internal  nasal  branch  of  the  ophthalmic  nerve. 

The  internal  surface  of  the  os  frontis  is  concave,  except  at 


OS    FRONTIS.  63 

the   orbitar    processes,    which  Fig.  11.* 

are  convex,  and  support  the 
anterior  lobes  of  the  brain. 
This  surface  is  not  so  smooth 
as  the  external ;  for  the  larger 
branches  of  the  arteries  of 
the  dura  mater  make  some 
furrows  in  its  sides  and  back 
parts,  and  its  lower  and  fore 
parts  are  marked  with  the 
convolutions  of  the  anterior 
lobes  of  the  brain.  In  the 
middle  of  the  concave  inter- 
nal surface  is  a  groove,  which 
is  small  at  its  commencement,  and  gradually  increases  in  dia- 
meter as  it  proceeds  upwards.  This  is  formed  by  the  superior 
longitudinal  sinus  ;  at  its  commencement  is  a  ridge  to  which  the 
beginning  of  the  falciform  process  of  the  dura, mater  is  attached. 
At  the  root  of  this  ridge  is  a  small  foramen,  sometimes  formed 
jointly  by  this  bone  and  the  ethmoid  ;  it  is  denominated  fora- 
men ccECum ;  in  it  a  small  process  of  the  falx  is  inserted,  and 
here  the  longitudinal  sinus  begins. 

The  frontal  sinuses  are  formed  by  the  separation  of  the  two 
tables  of  this  bone  at  the  part  above  the  nose  and  the  internal 
extremities  of  the  superciliary  ridges.  In  the  formation  of  these 
cavities,  the  external  table  commonly  recedes  most  from  the 
general  direction  of  the  bone. 

*  The  internal  surface  of  the  frontal  bone ;  the  bone  is  raised  in  such  a  man- 
ner as  to  show  the  orbito-nasal  portion,  i.  The  grooved  ridge  for  the  lodgment 
of  the  superior  longitudinal  sinus  and  attachment  of  the  falx.  2.  The  foramen 
caecum.  3.  The  superior  or  coronal  border  of  the  bone  ;  the  figure  is  situated 
near  that  part  which  is  bevelled  at  the  expense  of  the  internal  table.  4.  The 
inferior  border  of  the  bone.  5.  The  orbital  plate  of  the  left  side.  6.  The  cellu- 
lar border  of  the  ethmoidal  fissure.  The  foramen  ceecum  (2)  is  seen  through 
the  ethmoidal  fissure.  7.  The  anterior  and  posterior  ethmoidal  foramina  ;  the 
anterior  is  seen  leading  into  its  canal.  8.  The  nasal  spine.  9.  The  depression 
within  the  external  angular  process  (12)  for  the  lachrymal  gland.  10.  The  de- 
pression for  the  pulley  of  the  superior  oblique  muscle  of  the  eye  ;  immediately 
to  the  left  of  this  number  is  the  supra-orbital  notch,  and  to  its  right  the  internal 
angular  process.  11.  The  opening  leading  into  the  frontal  sinuses.  12.  The 
same  parts  are  seen  upon  the  opposite  side  of  the  figure. 


64  OSSA    PARIETALIA. 

These  cavities  are  divided  by  a  perpendicular  bony  partition, 
which  is  sometimes  perforated  and  admits  a  communication 
between  them.  Their  capacities  are  often  very  different  in 
different  persons,  and  on  the  different  sides  of  the  same  person. 
In  some  persons  whose  foreheads  were  very  flat,  they  are  said 
to  have  been  wanting.  They  communicate  with  the  nose  by 
means  of  a  canal  in  the  cellular  part  of  the  os  ethmoides. 

The  os  frontis  is  composed  *)f  two  tables,  and  an  interme- 
diate diploe,  as  the  other  bones  of  the  cranium  are  :  it  is  of  a 
mean  thickness  between  the  os  occipitis  and  the  parietal  bones ; 
and  is  nearly  equally  dense  throughout,  except  the  orbitar  pro- 
cesses, where,  by  the  action  of  the  eye  on  one  side,  and  pressure 
of  the  lobes  of  the  brain  on  the  other,  it  is  made  extremely  thin 
and  diaphanous,  and  the  diploe  is  entirely  obliterated.  In  this 
place  there  is  so  weak  a  defence  for  the  brain,  that  fencers 
esteem  a  push  in  the  eye  mortal. 

In  such  skulls  as  have  the  frontal  bone  divided  by  the  sagittal 
suture,  the  partition  separating  these  cavities  is  evidently  com- 
posed of  two  plates,  which  easily  separate. 

Each  of  the  frontal  sinuses  opens  into  one  of  the  uppermost 
cells  in  the' anterior  part  of  the  ethmoid  bone,  and  this  cell 
communicates  with  the  middle  channel  of  the  nose  under  the 
anterior  end  of  the  os  turbinatum  superius. 

This  bone  is  united  with  the  parietal,  ethmoidal  and  sphe- 
noidal  bones  of  the  head  ;  and  with  the  nasal,  maxillary,  ungui- 
form  and  malar  bones  of  the  face. 


Ossa  Parietalia. 

Each  of  the  two  ossa  parietalia  is  an  irregular  square  ;  its 
upper  and  front  edges  being  longer  than  the  one  behind  or 
below.  The  inferior  edge  is  concave,  the  middle  part  receiving 
the  upper  round  part  of  the  temporal  bone.  The  angle  formed 
by  the  under  and  anterior  edges  is  so  extended  as  to  have  the 
appearance  of  a  process. 

The  external  surface  of  each  os  parietale  is  convex.  Upon 
it,  somewhat  below  the  middle  height  of  the  bone,  there  is  a 


OSSA    PARIETALIA. 


65 


transverse    arched    ridge,    ge-  Fig.  12.* 

nerally  of  a  whiter  color 
than  any  other  part  of  the 
bone ;  from  which,  in  bones 
that  have  strong  prints  of 
muscles,  we  see  a  great  many 
converging  furrows,  like  so 
many  radii  drawn  from  a 
circumference  towards  a  cen- 
tre. From  this  ridge  of  each 
bone  the  temporal  muscle 
rises  :  and,  by  the  pressure  of  its  fibres,  occasions  the  furrows 
just  now  mentioned.  Below  these  we  observe,  near  the  semi- 
circular edges,  a  great  many  risings  and  depressions,  which  are 
joined  to  like  inequalities  on  the  inside  of  the  temporal  bone, 
and  form  the  squamous  suture.  Near  the  upper  edges  of  these 
bones,  towards  the  hind  part,  is  a  small  hole  in  each,  through 
which  a  vein  passes  from  the  teguments  of  the  head  to  the  lon- 
gitudinal sinus.f  o 

On  the  inner  concave  surface  of  the  parietal  bones  we  see  a 
great  many  deep  furrows,  disposed  somewhat  like  the  branches 
of  trees :  the  furrows  are  largest  and  deepest  at  the  lower  edge 
of  each  os  parietale,  especially  near  its  anterior  angle,  where  a 
complete  canal  is  sometimes  formed. 

[These  furrows  are  made  by  the  ramifications  of  the  great 
middle  artery  of  the  dura  mater:  they  have  been  commonly 
attributed  to  the  pulsation  of  the  artery  causing  the  absorp- 
tion of  the  bone,  but  it  is  more  probable  that  the  deposition  of 
the  bone  has  been  prevented  where  the  artery  beats,  and  thus 
the  bone  becomes  modelled  over  the  artery  in  the  same  way 
that  it  is  made  to  conform  to  the  surface  of  the  brain.  If  it 


*  The  external  surface  of  the  left  parietal  bone.  1 .  Superior  or  sagittal  border. 
2.  Inferior  or  squamous  border.  3.  Anterior  or  coronal  border.  4.  Posterior  or 
lambdoidal  border.  5.  The  temporal  ridge.  The  figure  is  situated  immediately 
over  the  parietal  protuberance.  6.  The  parietal  foramen,  unusually  large. 
7.  The  anterior  inferior  angle.  8.  The  posterior  inferior  angle. 

f  It  transmits,  also,  an  artery  from  the  integuments  to  the  dura  inater,  and 
is  called  the  parietal  foramen. — p. 

6* 


66  OSSA   TEMPORUM. 

were  exclusively  an  absorption  and  not  a  deposition,  we  should 
scarcely  find  the  artery  occasionally  surrounded  perfectly  by 
bone.] 

Fig.  13.*  On   the  inside  of  the  up- 

per edge  of  the  ossa  parie- 
talia  there  is  a  large  sinuos- 
ity, frequently  larger  in  the 
bone  of  one  side  than  of  the 
other,  where  the  upper  part 
of  the  falx  is  fastened,  and  the 
superior  longitudinal  sinus 
is  lodged.  Part  of  the  late- 
ral sinuses  generally  makes 
a  depression  near  the  angle 
formed  by  the  lower  and 
posterior  edges  of  these  bones ;  and  the  pits  made  by  the 
convolutions  of  the  brain  are  in  no  part  of  the  skull  more 
frequent  or  more  conspicuous,  than  in  the  internal  surface  of 
these  bones. 

The  ossa  parietalia  are  the  most  equal  and  smooth,  and  are 
among  the  thinnest  bones  of  the  cranium ;  but  they  enjoy  the 
general  structure  of  two  tables  and  diploe  most  perfectly. 

These  bones  are  joined  at  their  fore  side  to  the  os  frontis,  at 
their  long  inferior  angles,  to  the  sphenoid  bone  ;  at  their  lower 
edge,  to  the  ossa  temporum  ;  behind  to  the  os  occipitis,  or  ossa 
triquetra ;  and  above,  to  one  another. 

Ossa  Temporum.^ 
The  ossa  temporum  are  situated  at   the  lateral  and  inferior 

*  The  internal  surface  of  the  left  parietal  bone.  1.  The  superior,  or  sagittal 
border.  2.  The  inferior,  or  squamous  border.  3.  The  anterior,  or  coronal  border. 
4.  The  posterior,  or  larabdoidal  border.  5.  Part  of  the  groove  for  the  superior 
longitudinal  sinus.  6.  The  internal  termination  of  the  parietal  foramen.  7.  The 
anterior  inferior  angle  of  the  bone,  on  which  is  seen  the  groove  for  the  trunk  of 
the  arteria  meningea  media.  8.  The  posterior  inferior  angle,  upon  which  is  seen 
a  portion  of  the  groove  for  the  lateral  sinus. 

f  This  bone  has  received  the  name  of  temporal,  because  at  the  region  which 
it  covers,  the  hair  usually  commences  to  turn  gray,  and  thus  in  some  measure 
indicates  the  different  periods  of  life. — p. 


OSSA    TEMPORUM.  67 

parts  of  the  cranium  ;  each  of  them  is  divided  into  three  portions, 
a  superior  or  squamous,  a  posterior  or  rnastoid,  and  a  middle  or 
petrous. 

The  squamous  portion  is  nearly  semicircular  in  font!,  and 
very  thin ;  its  edge  is  sharp,  and  the  inner  table  appears  pared 
away  to  form  the  squamous  suture  •  with  the  corresponding 
edge  of  the  parietal  bone.  Its  external  surface  is  covered  by 
the  temporal  muscle.  At  the  lower  and  anterior  part  of  this 
surface,  the  zygomatic  process  arises,  it  proceeds  forward  to 
join  the  cheek  bone,  and  form  an  arch  under  which  the  tem- 
poral muscle  passes. 

At  the  base  of  the  process  is  the  glenoid  cavity  for  the  condyle 
of  the  lower  jaw.  Immediately  before  this  cavity  is  a  tubercle 
or  protuberance,  near  the  commencement  of  the  zygoma  and 
at  its  lower  border,  to  which  the  external  lateral  ligament  of 
the  lower  jaw  is  attached  ;  continued  horizontally  inwards 
from  the  tubercle  there  is  a  rounded  eminence,  called  the  emi- 
nentia  articularis,  which  forms  part  of  the  articular  surface  on 
which  the  condyle  rises  when  the  jaw  is  opened.  In  the  pos- 
terior part  of  the  cavity  is  a  fissure — called  the  glenoid — in 
which  part  of  the  ligament  of  this  articulation  is  fixed.  In 
this  fissure  is  an  aperture — glenoid  foramen — which  communi- 
cates with  the  cavity  of  the  tympanum  of  the  ear,  and  is  occu- 
pied by  a  small  nerve  called  chorda  tympani ;  and  also  by  the 
anterior  muscle  of  the  malleus — one  of  the  small  bones  of  the 
ear. 

The  internal  surface  of  the  squamous  portion  is  concave ;  it 
is  marked  by  pits  and  small  eminences,  which  correspond  with 
the  convoluted  surface  of  the  brain,  and  also  by  impressions  of 
the  arteries  of  the  dura  mater,  see  4  fig.  13,  as  they  go  towards 
the  parietal  bone. 

The  mastoid  or  occipital  portion  is  the  smallest  of  the  three 
parts  of  the  bone ;  it  consists  of  an  angular  portion,  which 
occupies  a  vacuity  between  the  occipital  and  parietal  bones ; 
and  of  the  mastoid  process.  The  mastoid  process  has  some 
resemblance  to  the  nipple;  it  is  composed  internally  of  cells 
which  communicate  with  the  cavity  of  the  tympanum.  On 


68  OSSA    TEMPORUM. 

the  internal  side  of  its  base  is  a  deep  groove  in  which  the  pos- 
terior belly  of  the  digastric  muscle  is  inserted.  Behind  this 
process  is  the  mastoid  hole,  which  transmits  a  vein,  and  some- 
times a  small  artery. 

On  the  internal  surface  of  this  portion  is  a  large  groove, 
which  is  formed  by  the  lateral  sinus.  The  mastoid  hole  above 
mentioned,  opens  into  this  groove. 

The  petrous  portion,  which  is  *  Fig.  14.* 

situated  between  the  squa- 
mous  and  mastoid,  resembles 
a  triangular  pyramid  lying  on 
one  of  its  sides.  When  in  its 
proper  position  it  projects 
inward  and  forward.  The 
two  upper  sides  form  a  por- 
tion of  the  internal  surface  of 
the  base  of  the  cranium.  The 
angle  formed  by  these  sur- 
faces is  very  prominent,  and  divides  the  fossa  for  the  middle 
lobes  of  the  brain,  or  rather  the  cavities  for  the  cerebrum  from 
those  which  contain  the  cerebellum. 

One  of  these  sides  of  the   petrous  portion  looks  forward  and 

outward,  the  other  backward  and  inward.     Each  of  them  has 

eminences  and  depressions  to  correspond  with  the  convolutions 

i  of  the  brain.     Near  the  middle  of  the  anterior  side  is  a  small 

j  furrow,    leading    to    a    foramen    denominated    Innominatum   or 

i  Hiatus  Fallopii  which  transmits  the  vidian  nerve  to   the  aque- 

i  duct  of  Fallopius. 

*  The  external  surface  of  the  temporal  bone  of  the  left  side.  1.  The  squamous 
portion.  2.  The  mastoid  portion.  3.  The  extremity  of  the  petrous  portion. 
4.  The  zygoma.  5.  Indicates  the  tubercle  of  the  zygoma,  and  at  the  same  time 
its  anterior  root  turning  inwards  to  form  the  eminenlia  articularis.  6.  The 
superior  root  of  the  zygoma,  forming  the  posterior  part  of  the  temporal  ridge. 

7.  The  middle  root  of  the  zygoma  terminating  abruptly  at  the  glenoid  fissure. 

8.  The  mastoid  foramen.     9.  The  meatus  auditorius  externus,  surrounded  by 
the  processus  auditorius.     10.  The  digastric  fossa,  situated  immediately  to  the 
inner  side  of  (2)  the  mastoid  process.     11.  The  styloid  process.     12.  The  vagi- 
nal process.     13.  The  glenoid  or  Glaserian  fissure ;  the  leading  line  from  this 
number  crosses  the  rough  posterior  portion  of  the  glenoid  fossa.     14.  The  open- 
ing and  part  of  the  groove  for  the  Eustachian  tube. 


OSSA    TEMPOREM.  69 

— There  is  another  small  oblique  foramen  immediately  beneath 
this,  which  transmits  the  nervous  petrosus  superjicialis  minor,  a 
branch  of  Jacobson's  nerve  ;  near  the  apex  of  the  petrous  por- 
tion of  the  temporal  bone  there  is  seen  a  large  forampn,  the 
termination  of  the  carotid  canal.  On  this  anterior  face  of  the 
bone,  especially  in  the  young  subject,  is  seen  a  rising  or  eminence 
running  from  base  to  apex,  which  is  formed  by  the  projection 
of  the  perpendicular  semicircular  canal. 

About  the  middle  of  the  posterior  side  is  the  large  aperture 
called  meatus  auditorius  internus.  The  bottom  of  this  cavity 
is  perforated  by  several  foramina  :  the  largest  and  uppermost 
of  which  is  the  orifice  of  a  winding  canal,  called  improperly 
the  aqueduct  of  Fallopius,  which  transmits  the  portio  dura  of 
the  seventh  pair  of  nerves.  The  other  foramina  transmit  the 
fibres  of  the  portio  mollis  of  the  same  nerve.  Posterior  to  the 
orifice  of  the  meatus  internus  is  an  oblong  depression,  with  a 
foramen  in  it,  covered  by  a  shell  of  bone,  which  is  the  orifice 
of  a  proper  aqueduct  or  canal  that  passes  from  the  vestibule  of 
the  ear.* 

— Neither  of  the  so  called  aqueducts  of  the  vestibule  or  cochlea, 
are  deserving  of  the  name  which  has  nevertheless  been  con- 
tinued to  designate  them,  since  we  no  longer  believe  with 
Cotugnius  their  discoverer,  that  they  are  a  sort  of  passages,  to 
admit  of  the  overflow  of  the  lymph,  when  it  was  secreted  in 
superabundance  in  the  labyrynth.  They  are  both  mere  open- 
ings, for  the  transmission  mainly  of  blood  vessels.  The  aque- 
duct of  the  vestibule  transmits  a  small  artery  and  vein  to  the 
vestibule,  and  lodges  a  process  of  the  dura  mater. — 

The  inferior  side  of  the  petrous  portioh  forms  a  part  of  the 
external  surface  of  the  basis  of  the  cranium.  On  the  back  part 
of  it  is  the  external  orifice  of  the  canal,  ^hrough  which  the 
portio  dura  passes.  It  is  called  foramen  stylo  mastoideum. 
Before  this  foramen  is  a  long  and  slender  styloid  process, 
which  varies  from  one  to  two  inches  in  length ;  it  projects 


*  This  orifice  should  not  be  confounded  with  one  which  is  nearer  to  the  meatus 
interims,  and  situated  on  the  angle  made  by  the  two  sides  of  the  bone. — H. 


70  OSSA    TEMPORUM. 

almost  perpendicularly  from  the  Fig.  15.* 

basis    of     the     cranium,     and 

gives  origin  to  a  muscle  of  the 

tongue,  of  the  os  hyoides,  and 

of  the    pharynx,  and    also  to 

several   ligaments.     The  base 

of  this   process  is   surrounded 

by  a   flat  projection  of  bone, 

occasionally  called  the  vaginal 

process. 

On  the  inside  of  this  pro- 
cess, and  rather  before  it,  is 
the  jugular  fossa,  which,  when  applied  to  a  corresponding  part 
of  the  occipital  bone,  makes  the  posterior  foramen  lacerum, 
through  which  the  internal  jugular  vein,  and  the  eighth  pair 
of  nerves  pass  out.  A  small  spine  called  the  jugular  process 
often  projects  into  this  foramen  from  the  temporal  bone,  and 
separates  the  nerve  from  the  vein  ;  the  nerve  being  anterior. 
— Upon  a  ridge  which  is  found  at  the  root  of  this  spine,  and 
just  behind  the  margin  of  the  carotid  foramen,  there  is  a  small 
opening  leading  into  the  canal  which  transmits  Jacobson's 
tympanic  branch  of  the  glosso-pharyngeal  nerve,  which  forms 


*  The  left  temporal  bone,  seen  from  within.  1.  The  squamous  portion. 
2.  The  mastoid  portion.  The  number  is  placed  immediately  above  the  inner 
opening  of  the  mastoid  foramen.  3.  The  petrous  portion.  4.  The  groove  for 
the  posterior  branch  of  the  arteria  meningea  media.  5.  The  bevelled  edge  of 
the  squamous  border  of  the  bone.  6.  The  zygoma.  7.  The  digastric  fossa 
immediately  internal  to  the  mastoid  process.  8.  The  occipital  groove.  9.  The 
groove  for  the  lateral  sinus.  10.  The  elevation  upon  the  anterior  surface  of  the 
petrous  bone  marking  the  situation  of  the  perpendicular  semicircular  canal. 
11.  The  opening  or  termination  of  the  carotid  canal.  12.  The  meatus  auditorius 
internus.  13.  A  dotted  line  leads  upwards  from  this  number  to  the  narrow 
fissure  which  lodges  a  process  of  the  dura  mater.  Another  line  leads  down- 
wards to  the  sharp  edge  which  conceals  the  opening  of  the  aquseductus  cochleae, 
while  the  number  itself  is  situated  on  the  bony  lamina  which  overlies  the  open- 
ing of  the  aquaeductus  vestibuli.  14.  The  styloid  process.  15.  The  stylo-mas- 
toid  foramen.  16.  The  carotid  foramen.  17.  The  jugular  process.  The  deep 
excavation  to  the  left  of  this  process  forms  part  of  the  jugular  fossa,  and  that  to 
the  right  is  the  groove  for  the  vein  of  the  cochlea.  18.  The  notch  for  the  fifth 
nerve  upon  the  upper  border  of  the  petrous  bone,  near  to  its  apex.  19.  The 
extremity  of  the  petrous  bone  which  gives  origin  to  the  levator  palati  and  tensor 
tympani  muscles. 


OSSA    TEMPORUM.  71 

an  important  part  of  the  nervous  plexus  of  the  tympanum. — 
Before  this  spine,  or  partition,  is  the  orifice  of  the  second  aque- 
duct of  the  ear,  the  aqueduct  of  the  cochlea,  through  which 
passes  a  vein  from  the  cochlea  to  the  internal  jugular, -6nd  in 
which  is  lodged  a  process  of  the  dura  mater.  This  jugular 
fossa  is  at  the  termination  of  the  groove,  in  the  internal  surface 
of  the  bone,  made  by  the  lateral  sinus.  At  a  small  distance 
before  the  jugular  fossa  is  the  commencement  of  the  carotid 
canal,  which  makes  a  curve  almost  semicircular,  and  then  pro- 
ceeds in  a  horizontal  course  to  the  anterior  extremity  of  the 
bone  :  through  this  winding  canal  passes  the  carotid  artery,  and 
the  filaments  from  the  fifth  and  sixth  pair  of  nerves,  which  are 
the  beginning  of  the  intercostal  or  sympathetic  nerve. 

Between  the  carotid  canal  and  the  cavity  for  the  condyle  of 
the  lower  jaw,  at  the  junction  of  the  anterior  part  of  the 
squamous  portion  with  the  petrous  portion  of  this  bone,  is  a 
very  rough  aperture,  the  bony  margin  of  which  appears  broken  ; 
this  is  the  orifice  of  the  bony  part  of  the  Eustachian  tube,  or 
passage  from  the  throat  to  the  ear.  This  canal  is  divided 
lengthwise  by  a  thin  bony  plate  ;  the  upper  passage  contains 
the  internal  muscle  of  the  malleus  bone  of  the  ear  (tensor 
tympani)  ;  the  lower  and  largest  canal  is  the  bony  part  of  the 
Eustachian  tube. 

The  external  passage  to  the  ear,  called  Meatus  Auditorius 
Externus,  is  situated  between  the  zygomatic  and  the  mastoid 
processes.  The  orifice  is  large  and  smooth  above,  but  rough 
below,  and  is  surrounded  by  a  rough  lip  called  the  auditory 
process.  The  direction  of  the  canal  is  obliquely  inward  and 
forward. 

— Angles  of  the  bone.  The  superior  angle  of  the  bone  which 
separates  the  anterior  and  posterior  faces,  is  sharp  and  gives 
attachment  to  the  tentorium  cerebelli.  It  is  slightly  grooved 
for  the  lodgment  of  the  superior  petrous  sinus,  and  near  its 
extremity  is  marked  by  a  smooth  notch,  upon  which  rests  the 
fifth  or  trigeminus  nerve.  The  anterior  angle  which  separates 
the  anterior  from  the  inferior  or  basilar  surface  of  the  bone,  is 
grooved  for  the  Eustachian  tube,  and  forms  the  posterior 


OS     OCCIPITIS. 


boundary  of  the  foramen  lacerum  anterius  of  the  base  of  the 
cranium.  The  posterior  angle  separating  the  posterior  from  the 
basilar  surface  of  the  bone,  is  grooved  for  the  inferior  petrous 
sinus  and  excavated  for  the  jugular  fossa  :  it  forms  the  anterior 
boundary  of  the  foramen  lacerum  posterius. — 

The  temporal  is  articulated  with  the  parietal,  occipital  and 
sphenoidal  bones,  and  by  its  zygomatic  process  with  the  malar 
bone. 

Os  Occipitis. 

The  occipital  bone  is  situated  at  the  posterior  and  inferior  part 

of  the  cranium  ;  it  is  of  a  rhomboidal  figure,  with  convex  and 

concave  surfaces. 

Fig.  16.*  The    upper     part    of     the 

external  surface  is  smooth  :  at 
a  small  distance  above  the 
middle  of  the  bone  is  the 
external  occipital  protube- 
rance, with  a  curved  line  on 
each  side  of  it.  Near  the 
middle  of  the  bone  the  tra- 
pezii  muscles  are  attached  to 
this  line,  and  externally,  on 
each  side,  the  occipito  fron- 
talis,  and  the  sterno  mas- 
toideus.  Under  this  line  is  a 
depression,  on  each  side,  into 

which    are    inserted    the   complexus    and    the    splenius   capitis 

muscles. 

Below  this  is  the  inferior  curved   line,  and  still    lower  is   a 

*  The  external  surface  of  the  occipital  bone.  1.  The  superior  curved  line. 
2.  The  external  occipital  protuberance.  3.  The  spine  or  vertical  ridge.  4.  The 
inferior  curved  line.  5.  The  foramen  magnum.  6.  The  condyls  of  the  right 
side.  7.  The  posterior  condyloid  fossa,  in  which  the  posterior  condyloid  foramen 
is  found.  8.  The  anterior  condyloid  foramen,  concealed  by  the  margin  of  the 
condyle.  9.  The  jugular  eminence  or  transverse  process  as  it  is  sometimes 
called.  10.  The  notch  in  front  of  the  jugular  eminence,  which  forms  part  of 
the  jugular  foramen.  11.  The  basilar  process.  12.  The  rough  projections  into 
which  the  moderator  ligaments  are  inserted. 


os  OCCIPITIS.  73 

muscular  depression  to  which  the  rectus  minor  posticus  is 
attached  on  each  side  near  the  middle  ;  and  the  rectus  major 
posticus,  and  obliquus  superior,  near  the  end. 

Below  the  protuberance  is  a  spine  which  passes  do\yn  the 
middle  of  the  bone,  and  at  the  lower  extremity  of  this  spine  is 
the  great  occipital  foramen,  which  forms  the  communication 
between  the  cavities  of  the  cranium,  and  the  vertebral  column. 
This  great  opening  transmits  the  medulla  spinalis  with  its 
membranes,  the  accessary  nerves  of  Willis,  and  the  vertebral 
arteries  and  veins. 

It  is  rather  of  an  oval  form,  and  the  occipital  condyles  are 
situated  anteriorly  on  its  edges.  These  condyles  are  of  an 
irregular  oval  figure  ;  they  are  not  parallel,  but  incline  towards 
each  other  anteriorly.  Their  articulating  surfaces  are  oblique, 
looking  downward  and  outward ;  they  are  received  into 
corresponding  cavities  of  the  atlas,  or  first  cervical  vertebra, 
and  form  with  them  the  articulation  of  the  head  and  neck. 
From  the  oblique  position  of  their  articulating  surfaces,  as  well 
as  the  length  of  their  ligaments  and  the  inclination  of  their 
axes  towards  each  other,  it  results,  that  their  motion  is  confined 
to  flexion  and  extension.  On  the  internal  sides  of  these 
condyles  is  a  rough  surface,  to  which  are  attached  the  strong 
ligaments  that  come  from  the  processus  dentatus  of  the  second 
vertebra  of  the  neck. 

Behind  each  condyle  is  a  depression  in  which  is  situated  the 
posterior  condyloid  foramen,  for  transmitting  the  cervical 
veins  ;  and  at  their  anterior  extremities  are  two  large  foramina, 
(anterior  condyloid,)  through  which  pass  the  ninth  pair  of 
nerves. 

On  the  internal  surface  of  the  os  occijfitis  is  the  crucial 
ridge,  to  which  are  attached  the  falx  cerebelli  or  vertical, 
and  the  tentorium  or  horizontal  process  of  the  dura  mater. 

The  groove  made  by  the  longitudinal  sinus  continues  from 
the  sagittal  suture  along  the  upper  limb  of  this  cross.  Some- 
times it  is  on  the  side  of  the  ridge,  and  sometimes  the  ridge  is 
depressed,  and  it  occupies  its  place ;  at  the  centre  of  the  cross, 
where  is  lodged  the  torcular  Herophili,  formed  by  the 
7 


74 


OS    OCCIPITIS. 


common   junction  of  the  sinuses,  the  groove   for   the  longitu- 
dinal  sinus   divides   into  two  grooves  for   the   lateral   sinuses ; 
Fig.   17.*  these    form     the     horizontal 

limbs  of  the  cross,  and  pro- 
ceed towards  the  foramen 
lacerum  where  the  lateral 
sinuses  emerge  from  the 
cavity  of  the  cranium.  The 
lower  limb  of  the  cross  is 
formed  by  a  spine  which  pro- 
ceeds from  the  centre  of  the 
bone  to  the  great  occipital  fora- 
men, and  supports  the  falx  of 
the  cerebellum.  The  internal 
surface  of  the  bone  is  divided 
by  the  cross  into  four  por- 
tions, each  of  which  is  con- 
siderably depressed  so  as  to  form  fossae ;  the  two  upper  by  the 
posterior  lobes  of  the  cerebrum,  and  the  lower  by  those  of  the 
cerebellum. 

This  circumstance  occasions  great  inequality  in  the  thickness 
of  the  bone,  as  the  depressed  portions  are  extremely  thin,  while 
the  ridge  adds  greatly  to  the  thickness,  especially  at  the  centre 
of  the  cross,  which  is  opposite  to  the  great  external  protuber- 
ance. 

Before  the  great  occipital  foramen  is  the  cuneiform  process, 
which  is  thick  and  substantial ;  it  terminates  by  a  broad 
truncated  extremity,  that  is  articulated  with  the  body  of  the 
sphenoid  bone.  The  internal  surface  of  the  cuneiform  process 

*  The  internal  surface  of  the  occipital  bone.  1.  The  left  cerebral  fossa. 
2.  The  left  cerebellar  fossa.  3.  The  groove  for  the  posterior  part  of  the  superior 
longitudinal  sinus.  4.  The  spine  for  the  falx  cerebelli,  and  groove  for  the 
occipital  sinuses.  5.  The  groove  for  the  left  lateral  sinus.  6.  The  internal 
occipital  protuberance  which  lodges  the  torcular  Herophili.  7.  The  foramen 
magnum.  8.  The  basilar  process,  grooved  for  the  medulla  oblongata.  9.  The 
termination  of  the  groove  for  the  lateral  sinus,  bounded  externally  by  the  jugu- 
lar eminence.  10.  The  jugular  fossa  •  this  fossa  is  completed  by  the  petrous 
portion  of  the  temporal  bone.  11.  The  superior  border.  12.  The  inferior  border. 

13.  The  border  which  articulates  with  the  petrous  portion  of  the  temporal  bone. 

14.  The  anterior  condyloid  foramen. 


OS    ETHMOIDES.  75 

is  somewhat  excavated,  and  forms  a  large  superficial  groove  for 
the  medulla  oblongata  ;  on  each  side  of  this  groove  is  a  small 
furrow  for  the  inferior  petrous  sinuses. 

The  two  upper  edges  of  the  occipital  bone  are  serrated,  to 
articulate,  with  those  of  the  parietal,  and  form  the  lambdoidal 
suture.  The  inferior  edges  are  divided  into  two  portions  by  a 
small  prominence  called  the  jugular  eminence ;  the  upper  and 
posterior  portion  is  also  serrated  for  articulation  with  the 
mastoid  portion  of  the  temporal ;  the  inferior  portion,  which 
is  not  serrated,  applies  to  the  petrous  portion  of  the  temporal 
bone,  and  a  notch  in  it  contributes  to  the  formation  of  the  fora- 
men lacerum. 

The  upper  angle  of  this  bone  is  acute,  the  lateral  angles  are 
obtuse,  and  the  inferior  truncated.  It  is  articulated  with  the 
parietal,  the  temporal,  and  the  sphenoidal  bones. 

Os  Ethmoides. 

The  05  ethmoides  is  truly  one  of  the  most  curious  bones  of 
the  human  body.  It  appears  almost  a  cube,  not  of  solid  bone, 
but  exceedingly  light  and  spongy,  and  consisting  of  many  con- 
voluted plates,  which  form  a  network  like  honey-comb.  It  is 
firmly  enclosed  in  the  os  frontis,  betwixt  the  orbitary  processes 
of  that  bone.  One  horizontal  plate  receives  the  olfactory  nerves, 
which  perforate  that  plate  with  such  a  number  of  small  holes, 
that  it  resembles  a  sieve  ;  whence  the  bone  is  named  cribriform, 
or  ethmoid.  "  Other  plates  are  so  arranged  that  they  form  a 
cellular  structure,  on  which  the  olfactory  nerves  are  expanded 
by  means  of  a  particular  membrane ;  while  an  additional  plate, 
appropriated  to  the  nose,  descends  into  that  cavity  in  a  perpen- 
dicular direction,  and  forms  a  large  proportion  of  the  partition 
which  divides  it  into  two  chambers. 

The  cribriform  plate  is  situated  in  the  anterior  part  of  the 
basis  of  the  cranium.  The  cellular  part  occupies  most  of  the 
space  between  the  orbits  of  the  eyes,  and  the  perpendicular  plate 
is  to  be  found  in  the  septum  of  the  nose. 

The  ethmoid  bone,  for  the  purposes  of  description,  may  be  , 
divided  into  three  parts,  viz.  the  cribriform  plate,  the  nasal  or  ( 
perpendicular  lamella,  and  the  cellular  portions.  , 


76  OS    ETHMOIDES. 

The  cribriform  plate  is  oblong  in  shape,  and  firm  in  its 
structure  ;  in  the  middle  of  the  anterior  extremity  the  crista 
galli  projects  from  its  upper  surface,  dividing  it  into  two  lateral 
portions,  each  of  which  is  rather  concave,  and  occupied  by  the 
bulbous  extremity  of  the  olfactory  nerve  ;  it  is  perforated  by 
many  foramina,  which  transmit  the  fibres  of  the  aforesaid 
nerve.  Near  the  crista  galli,  on  each  side,  there  is  a  small  fis- 
sure, through  which  passes  a  nCrvous  filament  derived  from  the 
ophthalmic  branch  of  the  fifth  pair.  The  crista  galli  varies  in  size 
in  different  subjects :  the  beginning  of  the  falciform  process  of 
the  dura  mater  is  attached  to  it,  and  with  the  opposite  part  of 
the  os  frontis  it  forms  the  foramen  ca3cum,  already  mentioned. 
It  is  very  conspicuous  in  the  basis  of  the  cranium. 

The  nasal  plate  of  the  ethmoid  bone  seems  to  be  continued 
downwards  from  the  crista  galli  through  the  cribriform  plate.  It 
is  thin,  but  firm  ;  it  forms  the  upper  portion  of  the  septum  of 
the  nose,  and,  to  complete  the  partition,  it  unites  with  the  vomer 
and  with  a  plate  of  cartilage  before.  It  is  very  often  inclined 
to  one  side,  so  that  the  nostrils  are  not  of  equal  size. 

At  a  small  distance  from  this  perpendicular  plate,  on  each 
side  of  it,  the  cellular  portions  originate  from  the  lower  surface 
of  the  cribriform  plates ;  they  extend  from  before  backward, 
and  are  as  long  as  the  ethmoid  bone ;  their  breadth  between 
the  eye  and  the  cavity  of  the  nose  varies  in  different  subjects, 
from  half  an  inch  to  more ;  they  extend  downwards  from  the 
root  of  the  nose  or  from  the  cribriform  plate,  more  than  half 
way  to  the  roof  of  the  mouth.  Their  external  surface  on  each 
side  forms  a  part  of  the  surface  of  the  orbit  of  the  eye,  and  is 
called  05  planum ;  their  internal  surface  forms  part  of  the 
external  lateral  surface  of  each  nostril.  This  surface  extends 
the  whole  depth  of  the  nostril,  from  before  backward  ;  but  in 
many  skeletons  it  is  extremely  imperfect,  owing  to  the  great 
brittleness  of  the  bony  plates  of  which  it  is  composed.  When 
the  bone  is  perfect,  the  uppermost  half  part  of  this  internal 
surface  is  uniformly  flat,  and  rather  rough  ;  but  below  it,  about 
the  middle  of  the  bone,  a  deep  groove  begins,  which  extends 
downwards  and  backwards,  to  the  posterior  extremity  ;  this  is 


OS    ETHMOIDES.  77 

the  upper  channel  or  meatus  of  the  nose.  The  edge  of  the 
surface  immediately  above  it  projects  in  a  small  degree  over 
this  channel  or  groove ;  having  been  described  by  Morgagni,  it 
bears  his  name,  and  may  be  considered  as  one  of  the"~^pongy 
or  turbinated  bones ;  from  its  situation,  it  should  be  called  the 
first  or  superior.  The  groove  is  very  deep,  and  most  of  the  cells 
of  the  posterior  part  of  the  ethmoid  bone  communicate  with  it, 
through  one  or  more  foramina  at  its  anterior  extremity. 

The  part  of  the  surface  of  the  ethmoid  which  is  immediately 
below  this  groove,  is  convex ;  that  which  is  before  and  below 
it,  is  rather  flat ;  the  convex  part  is  the  middle  spongy  or 
turbinated  bone,  as  it  has  commonly  been  called ;  it  projects 
obliquely  into  the  cavity  of  the  nose,  and  hangs  over  the  middle 
channel  or  meatus,  which  is  immediately  below  the  ethmoid 
bone.  The  internal  surface  of  this  spongy  bone,  which  is 
opposite  the  septum  of  the  nose,  is  convex  and  rough  or  spongy  ; 
the  external  surface  is  concave.  The  anterior  cells  of  the 
ethmoid,  and  particularly  those  which  the  frontal  sinuses  on 
each  side  communicate  with,  open  into  the  middle  channel  or 
meatus,  under  the  anterior  end  of  this  turbinated  bone. 

This  middle  channel  or  meatus,  is  much  larger  than  that 
above  ;  it  extends  from  the  anterior  to  the  posterior  part  of  the 
nostrils,  and  slopes  downwards  and  backwards.  The  cavity  of 
the  upper  maxillary  bone,  or  the  antrum  highmorianum,  opens 
on  each  side  into  this  meatus,  and  a  thin  plate  of  bone  extends 
from  the  cellular  part  of  the  ethmoid  so  as  to  cover  a  part  of  it. 

The  cellular  portions  of  the  ethmoid  are  composed  of  plates 
thinner  than  the  shell  of  an  egg ;  they  are  entirely  hollow,  and 
the  cells  are  very  various,  in  number,  size,  and  shape.  Some 
cells  of  the  uppermost  row  communicate  with  those  of  the 
os  frontis,  formed  by  the  separation  of  the  plates  of  the  orbitar 
process  of  that  bone. 

From  the  posterior  part  of  the  cribriform  plate,  where  it  is 
in  contact  with  the  lesser  wings  of  the  sphenoidal  bone,  thin 
plates  of  bone  pass  down  upon  the  anterior  surface  of  the  body 
of  the  os  sphenoides,  one  on  each  side  of  the  azygos  process, 
and  often  diminish  the  opening  into  the  sphenoidal  cells. 
These  plates  are  sometimes  triangular  in  form,  the  basis  uniting 
7* 


78  OS    ETHMOIDES. 

with  the  cribriform  plate.  They  have  been  described  very 
differently  by  different  authors,  some  considering  them  as 
belonging  to  the  os  ethmoides,  and  others  to  the  sphenoid  bone. 
To  the  perfect  ethmoid  bone  there  are  attached  two  triangular 
pyramids,  in  place  of  the  triangular  bones;  these  pyramids  are 
hollow,  the  azygos  process  of  the  os  sphenoides  is  received 
between  them ;  one  side  of  each  pyramid  applies  to  each  side 
of  the  azygos  process,  another  side  applies  to  the  anterior 
surface  of  the  body  of  the  sphenoid  bone,  in  place  of  the  ossa 
triangularia,  and  the  third  side  is  the  upper  part  of  one  of  the 
posterior  nares.*5  There  are  two  apertures  in  each  of  these 

*  This  may  be  considered  as  an  original  observation  of  the  lamented  "Wistar. 
The  merit  of  it  has  been  denied  to  him,  more  particularly  by  the  anatomists  of 
Paris,  under  an  impression  that  he  had  been  anticipated  in  it  by  Berlin,  who 
has  written  an  excellent  and  minute  treatise  on  osteology.    The  extent  to  which 
the  claims  of  other  anatomists  interfere  with  his,  he  was  fully  aware  of;  and  it 
will  be  seen  by  the  following  communications  to  the  American  Philosophical 
Society,  that  these  are  placed  in  as  important  a  light  as  they  deserve,  at  the 
same  time  that  he  vindicates  his  own  pretensions,  to  have  first  observed  the 
"  cornets  sphenoidaux  "  in  the  form  of  triangular  hollow  pyramids,  as  consti- 
tuting part  of  the  perfect  ethmoid  bone. — H. 

Observations  on  those  Processes  of  the  Ethmoid  Bone  which  originally  form  the  Sphe- 
noid  Sinuses.     By  C.    Wistar,  M.  D.,  President  of  the  Society,  Professor  of 
Anatomy  in  the  University  of  Pennsylvania. — Read,  Nov.  4,  1814. 
It  has  been  long  believed  that  the  sinuses,  or  cavities  in  the  body  of  the  os 
sphenoides,  were  exclusively  formed  by  that  bone,  when  Winsl6w  suggested 
that  a  small  portion  of  the  orbitar  processes  of  the  ossa  palati  contributed  to 
their  formation.* 

Many  year's  after  Winslow's  publication,  Monsieur  Berlin  described  two 
bones  which  form  the  anterior  sides  of  these  sinuses,  and  contain  the  foramina 
by  which  they  communicate  with  the  nose.f 

These  bones  he  denominates  "Cornets  Sphenoidaux,"  and  states  that  they 
are  most  perfect  and  distinct  between  the  ages  of  four  years  and  twenty  ;  that 
they  are  not  completely  formed  before  this  period,  and  that  after  it  they  appear 
like  a  part  of  the  sphenoidal  bone.— According  to  his  account  they  are  lamina  of 
a  triangular  form,  and  are  originally  in  contact  with  the  anterior  and  inferior 
surface  of  the  body  of  the  os  sphenoides,  so  that  they  form  a  portion  of  the  sur- 
face of  the  cavity  of  the  nose. — He  believed,  that  as  they  increase  in  size,  they 
become  convex  and  concave,  and  present  their  concave  surfaces  to  the  body  of 
the  sphenoidal  bone,  which  also  becomes  concave,  and  presents  its  concavity  to 
those  bones;  thus  forming  the  sinuses. 

*  In  his  description  of  the  Ossa  Palati,  printed  in  the  Memoirs  of  the  Academy  of 
Sciences  for  1720. 

t  See  Memoirs  of  the  Academy  of  Sciences  for  1774. 


t         Cr    f 

^/t  Vr^^^*^ 


OS    ETHMOIDES.  79 

pyramids  ;  one  at  the  base  opening  directly  into  the  nose,  near 
the  situation  of  the  opening  of  the  sphenoida).  sinuses,  in  the 
bones  of  adults  ;  and  the  other  in  each  of  the  sides  in  contact 
with  the  azygos  process.  './ 

This  account  of  M.  Berlin  has  been  adopted  by  Sabatier,  and  also  by  Boyer, 
who  has  improved  it  by  the  additional  observation,  that  these  triangular  bones 
are  sometimes  united  to  the  ethmoid,  and  remain  attached  to  that  bone  when  it 
is  separated  from  the  os  sphenoides.  Bichat  and  Fyfe  have  confirmed  the 
description  of  Boyer. 

The  specimens  of  ethmoid  and  sphenoid  bones,  herewith  exhibited  to  the 
society,  will  demonstrate  that  in  certain  subjects,  about  two  years  of  age,  there 
are  continued  from  the  posterior  part  of  the  cribriform  plate  of  the  ethmoid,  two 
Hollow  Triangular  Pyramids,  which,  when  in  their  proper  situations,  receive  be- 
tween them  the  azygos  process  of  the  os  sphenoides.— (See  Plate  X.  Figures  1, 
2,  3,  with  the  explanation.) 

The  internal  side  of  each  of  these  pyramids  applies  to  the  aforesaid  azygos 
process ;  the  lower  side  of  each  forms  part  of  the  upper  surface  of  the  posterior 
nares  ;  the  external  side  at  its  basis  is  in  contact  with  the  orbit ar  process  of  the 
os  palati.  The  base  of  each  pyramid  forms  also  a  part  of  the  surface  of  the 
posterior  nares,  and  contains  a  foramen  which  is  ultimately  the  opening  into  the 
sphenoidal  sinus  of  that  side. 

In  the  sphenoidal  bones,  which  belong  to  such  ethmoids  as  are  above  described, 
there  are  no  cells  or  sinuses  ;  for  the  pyramid  of  the  ethmoid  bones  occupy  their 
places.  The  azygos  process,  which  is  to  become  the  future  septum  between  the 
sinuses,  is  remarkably  thick,  but  there  are  no  cavities  or  sinuses  in  it. 

The  sides  of  the  pyramids,  which  are  in  contact  with  this  process,  are  ex- 
tremely thin,  and  sometimes  have  irregular  foramina  in  them,  as  if  their  osseous 
substance  had  been  partially  absorbed.*  That  part  of  the  external  side  of  the 
pyramid  which  is  in  contact  with  the  orbitar  process  of  the  os  palati  is  also  thin, 
and  sometimes  has  an  irregular  foramen,  which  communicates  with  the  cells  of 
the  aforesaid  orbitar  process. 

Upon  comparing  these  perfect  specimens  of  the  ethmoid  and  sphenoidal  bones 
of  the  subject  about  two  years  of  age,  with  the  os  sphenoides  of  a  young  subject 
who  was  more  advanced  in  years,  it  appears  probable  that  the  azygos  process 
and  the  sides  of  the  pyramid  applied  to  it,  are  so  changed,  in  their  progress  of 
life,  that  they  simply  constitute  the  septum  between  the  sinuses ;  that  the  exter- 
nal side  of  the  pyramid  is  also  done  away,  and  that  the  front  side  and  the  basis 
of  the  pyramid  only  remain ;  constituting  the  Cornets  Sphenoidaux  f  of  M. 
Berlin. 

If  this  be  really  the  case,  the  origin  of  the  sphenoidal  sinuses  is  very  intel- 
ligible. 

* 

*  See  e,  Fig.  3. 

t  "  Cornet"  is  the  word  applied  by  several  French  anatomists  to  the  Ossa  Turblnati  of 
the  nose  ;  they  seem  to  have  intended  to  express  by  it  a  convoluted  lamina  or  plate  of  bone. 

The  fine  drawing  of  the  Ethmoid  Bone,  for  this  plate  was  done  by  my  friend  M.  Lesueur, 
•whose  talents  are  so  conspicuous  in  the  plates  attached  to  Peron's  "  Voyage  de  Descou- 
vertes  aux  Terres  Australes. 


80  OS    SPHENOIDES. 

.» 

Os  Sphenoides. 

The  os  sphenoides  or  pterygoideus,  resembles  a  bat  with  its 
wings  extended.  It  consists, 

/    1st.  Of  a  body  with  two  processes  arising  from  it,  called  the 
lesser  wings,  or  apophyses  of  Ingrassias. 

2dly.  Of  two  large  lateral  processes,  called  the  greater  wings, 
or  temporal  processes  ;  and, 

3dly.  Of  two  vertical  portions,  denominated  pterygoid  pro- 
cesses. 

The  body  is  situated  near  the  centre  of  the  cranium,  and  in 
contact  with  the  cuneiform  process  of  the  occipital  bone  ;  the 
greater  wings  extend  laterally  between  the  frontal  and  temporal 
bones  as  high  as  the  parietal ;  while  the  pterygoid  processes 
pass  downwards  on  each  side  of  the  posterior  opening  of  the 
nose,  as  low  as  the  roof  of  the  mouth.  It  is,  therefore,  in 
contact  with  all  the  other  bones  of  the  cranium,  and  with  many 
bones  of  the  face. 

The  body  has  a  cubic  figure ;  its  upper  surface  forms  a  portion 
of  the  basis  of  the  cranium ;  its  lower  and  anterior  surfaces  form 

/      Explanation  of  the  Figures  in  the  Plate  referred  to  above. 

FIG.  I. 

Represents  the  upper  surface,  or  cribriform  plate  of  the  Ethmoid  Bone. 
a.  CristaGalli. 
bbbb.  Cribriform  plate. 
c.  Surface  denominated  Os  Planum. 
d  d.  Hollow  Triangular  Pyramids. 

e.  Space  between  the  Pyramids  for  receiving  the  Azygos  Process  of  the  Os 
Sphenoides. 

FIG.  II. 

A  lateral  View  of  the  Bone. 
a.  Crista  Galli. 

c.  Os  Planum. 

d.  Triangular  Pyramid. 

FIG.  III. 

The  Bone  Inverted. 
a.  The  Nasal  Plate  of  the  Ethmoid  Bone,  which  constitutes  the  upper  portion 

of  the  Septum  of  the  nose. 
g  g.  Those  portions  of  the  Ethmoid  which  are  called  Superior  Turbinated 

Bones. 

//.  The  Cellular  Lateral  Portions  of  the  Bone. 
d  d.  The  Triangular  Pyramids. 

e.  Space  between  the  Pyramids  for  the  Azygos  Process  of  the  Os  Sphenoides 
— a  foramen  on  the  internal  side  of  one  of  the  Pyramids. 


s 


i 


OS    SPHENOIDES.  81 

part  of  the  cavity  of  the  nose ;  the  posterior  surface  is  articu- 
lated  with   the   cuneiform   process  of  the  occipital  bone ;  and 
laterally  it  is  extended  into  the  great  wings,  or  temporal  processes. 
On   the  upper  surface  of  the  body,  the  lesser  wings^br  the 
apophyses  of  Ingrassias,*  project  from  the  lateral  and  anterior 
parts ;    these  wings  consist   of  two    triangular   plates,  each    of 
Fig.  18.f  which  is  joined   to   the 

other  by  its  base,  and 
to  the  body  of  the  os 
sphenoides  by  its  un- 
der surface  near  the 
base,  and  terminates 
in  a  point ;  their  direc- 
tion is  forwards  and 
outwards,  and  their  flat 
surfaces  are  horizontal.  Anteriorly  they  are  connected  by 
suture  to  the  ethmoid  and  frontal  bones  ;  their  posterior  edge 
is  rounded,  and  detached  from  any  other  bone,  forming  the 
upper  margin  of  the  foramen  lacerum  of  the  orbit  of  the  eye ; 
this  edge  is  thick  and  prominent  at  its  internal  extremity,  and 
these  prominences  are  called  the  anterior  or  clinoid  processes  ; 

*  A  physician  of  Palermo,  who  died  in  1580,  aged  70. — H. 

f  The  superior  or  cerebral  surface  of  the  sphenoid  bone.  1.  The  processus 
olivaris.  2.  The  ethmoidal  spine.  3.  The  lesser  wing  of  the  left  side.  4.  The 
cerebral  surface  of  the  greater  wing  of  the  same  side.  5.  The  spinous  process. 
6.  The  extremity  of  the  pterygoid  process  of  the  same  side,  projecting  down- 
wards from  the  under  surface  of  the  body  of  the  bone.  7.  The  foramen  opticum. 
8.  The  anterior  clinoid  process.  9.  The  groove  by  the  side  of  the  Sella  Turcica, 
for  lodging  the  internal  carotid  artery,  cavernous  plexus,  cavernous  sinus,  and 
orbital  nerves.  10.  The  Sella  Turcica.  11.  The  posterior  boundary  of  the  Sella 
Turcica ;  its  projecting  angles  are  the  posterior  clinoid  processes.  12.  The 
basilar  portion  of  the  bone.  13.  Part  of  the  sphenoidal  fissure.  14.  The  foramen 
rotundum.  15.  The  foramen  ovale.  16.  The  foramen  spinosum.  17.  The 
angular  interval  which  receives  the  apex  of  the  petrous  portion  of  the  temporal 
bone.  The  posterior  extremity  of  the  Vidian  canal  terminates  at  this  angle. 
18.  The  spine  of  the  spinous  process ;  it  affords  attachment  to  the  internal  lateral 
ligament  of  the  lower  jaw.  19.  The  border  of  the  greater  wing  and  spinous 
process  which  articulates  with  the  anterior  part  of  the  squamous  portion  of  the 
temporal  bone.  20.  The  internal  border  of  the  spinous  process,  which  assists 
in  the  formation  of  the  foramen  lacerum  basis  cranii.  21.  That  portion  of  the 
greater  ala  which  articulates  with  the  anterior  inferior  angle  of  the  parietal  bone. 
22.  The  portion  of  the  greater  ala  which  articulates  with  the  orbital  process  of 
the  frontal  bone. 


82  OS    SPHENOIDES. 

immediately  before  them  are  the  optic  foramina,  which  pass 
obliquely  through  the  wings  into  the  orbit  of  the  eye,  and 
transmit  on  each  side  the  optic  nerve  and  a  small  artery. 

Behind  the  optic  foramen  is  a  notch  and  sometimes  a  foramen, 
made  by  the  carotid  artery.  When  the  notch  is  converted  into 
a  foramen,  it  is  by  a  small  bony  pillar  being  extended  from  the 
anterior  clinoid  process,  to  the  body  of  the  sphenoid.  A  groove 
made  by  the  optic  nerves,  is  cften  seen  extending  across  the 
body  of  the  bone,  from  one  of  the  optic  foramina  to  the  other. 
Behind  it  is  a  depression,  which  occupies  the  greatest  part  of  this 
surface  of  the  bone,  in  which  the  pituitary  gland  is  lodged  ;  the 
back  part  of  this  depression  is  bounded  by  a  transverse  emi- 
nence, called  the  posterior  clinoid  process.  These  three  pro- 
cesses are  called  clinoid  from  their  supposed  resemblance  to  the 
supporters  of  a  bed ;  and  the  depression  for  the  pituitary  gland 
is  called  sella  turcica  from  its  resemblance  to  the  saddle  used  by 
the  Turks. 

On  each  side  of  the  posterior  clinoid  process  is  a  groove  in 
the  body  of  the  bone,  made  by  the  carotid  artery  as  it  passes 
from  the  foramen  caroticum  of  the  temporal  bone.  The  posterior 
surface  of  the  body  of  the  sphenoides  is  rough,  for  articulation 
with  the  truncated  end  of  the  cuneiform  process  of  the  os 
occipitis. 

On  the  anterior  and  inferior  surfaces  is  a  spine,  called  the 
azygos  process,  or  rostrum  which  is  received  into  the  base  of 
the  vomer,  and  extends  forward  until  it  meets  the  nasal  plate  of 
the  ethmoid  bone  ;  on  each  side  of  this  spine,  in  the  anterior 
surface,  are  the  orifices  of  the  sphenoidal  cells.  Those  orifices 
appear  very  differently  in  different  bones ;  in  some  very  perfect 
specimens,  they  are  irregularly  oval,  being  closed  below  and 
on  their  external  sides,  by  the  processes  of  the  ossa  palati,  and 
above  by  the  triangular  plates,  as  they  have  been  called,  of 
the  ethmoid  bone.  The  cells  or  sinuses,  to  which  these 
orifices  lead,  occupy  the  body  of  the  sphenoidal  bone ;  they  are 
divided  by  a  partition,  and  each  of  them  has  a  communication 
with  the  cavity  of  the  nose  on  its  respective  side,  by  the  orifice 
above  described.  The  sinuses  do  not  exist  during  infancy ; 
they  increase  in  the  progress  of  life,  and  are  very  large  in  old  age. 


OS    SPHENOIDES.  83 

Laterally,  the  body  of  the  sphenoides  is  extended  into  the 
portions  called  the  great  wings  or  temporal  processes.  These 
great  wings  compose  the  largest  part  of  the  bone,  and  their 
internal  surface  forms  a  portion  of  the  middle  fossa  of  the/  base 
of  the  cranium.  Externally,  the  surface  of  each  great  wing  is 
divided  into  two  portions  :  one  of  which  is  lateral,  and  unites 
to  the  frontal,  temporal,  and  malar  bones,  forming  part  of  the 
smooth  surface  for  the  temporal  muscle ;  the  other  portion 
forms  part  of  the  orbit  of  the  eye,  and  is  very  regular  and 
smooth.  As  the  ethmoid  bone  forms  part  of  the  inside,  this 
portion  of  the  great  wing  forms  part  of  the  outside  of  the  orbit, 
and  is  termed  the  orbitary  process  of  the  sphenoid  bone.  The 
horizontal  part  of  each  wing  terminates  in  an  acute  angle 
termed  spinous  process,  which  penetrates  between  the  petrous 
portion  and  the  articulating  cavity  of  the  temporal  bone.  In 
this  angle  is  the  foramen  for  the  principal  artery  of  the  dura 
mater  ;  near  the  point  of  the  angle  is  a  small  process,  which 
projects  from  the  basis  of  the  cranium,  and  is  called  styloid. 

Fig.  19.*  The     pterygoid      pro- 

cesses pass  downwards  in 
a  direction  almost  per- 
pendicular to  the  base  of 
the  skull.  Each  of  them 
has  two  plates,  and  a 
middle  fossa  facing  back- 
wards ;  to  complete  the 
comparison,  they  should 
be  likened  to  the  legs  of  the  bat,  but  are  inaccurately  named 
pterygoid,  or  wing-like  processes.  The  external  plates 
are  broadest,  and  the  internal  are  longest.  From  each  side  of 

*  The  antero-inferior  view  of  the  sphenoid  bone.  1.  The  ethmoid  spine. 
2.  The  rostrum.  3.  The  sphenoidal  spongy  bone,  partly  closing  the  left  opening 
of  the  sphenoidal  cells.  4.  The  lesser  wing.  5.  The  foramen  opticum  piercing 
the  base  of  the  lesser  wing.  6.  The  sphenoidal  fissure.  7.  The  foramen  rotun- 
dum.  8.  The  orbital  surface  of  the  greater  wing.  9.  Its  temporal  surface.  10. 
The  pterygoid  ridge.  11.  The  pterygo-palatine  canal.  12.  The  foramen  of 
entrance  to  the  Vindian  canal.  13.  The  internal  pterygoid  plate.  14.  The 
hamular  process.  15.  The  external  pterygoid  plate.  16.  The  foramen  spino- 
sum.  17.  The  foramen  ovale.  18.  The  extpemity  of  the  spinous  process  of 
the  sphenoid. 


84  FORAMINA  OF   THE  SPHENOIDAL  BONE. 

the  external  plates  the  pterygoid  muscles  take  their  rise.  At 
the  root  of  each  internal  plate,  a  small  hollow  may  be  remarked, 
where  the  musculus  circumflexus  palati  rises,  and  part  of  the 
cartilaginous  end  of  the  Eustachian  tube  rests.  At  the  lower 
end  of  the  plate  is  a  hook-like  process  (hamulus)  round  which 
the  tendon  of  the  last  named  muscle  plays,  as  on  a  pulley.  The 
ossa  palati,  on  each  side,  rest  upon  these  internal  plates ;  and, 
therefore,  the  pterygoid  processes  seem  to  support  the  whole 
face. 

Foramina  of  the  Sphenoidal  Bone. 

Before  these  foramina  are  described,  it  is  necessary  to  state,  that  the  nerves  of 
the  brain  are  named  numerically,  beginning  with  the  olfactory,  which  is 
foremost. 

It  should  also  be  observed,  that  each  nerve  of  the  fifth  pair  is  divided,  before  it 
passes  from  the  cavity  of  the  cranium,  into  three  large  branches. 

The  first  foramina  are  the  optic,  which  have  been  already 
described;  they  transmit  the  optic,  or  second  pair  of  nerves, 
and  a  small  artery,  to  the  ball  of  the  eye. 

The  second  foramen,  on  each  side,  is  the  foramen  lacerum. 
It  commences  largely  at  the  sella  turcica,  and  extends  laterally 
a  considerable  distance,  until  it  is  a  mere  fissure.  The  upper 
margin  of  this  foramen  is  formed  by  the  anterior  clinoid 
processes,  and  the  edges  of  the  smaller  wings  of  the  sphenoid 
bone.  This  foramen  transmits  the  third,  fourth,  and  sixth  pair 
of  nerves,  and  the  first  branch  of  the  fifth  pair,  to  the  muscles, 
and  the  other  parts,  subservient  to  the  eye. 

The  foramen  rotundum,  or  third  hole,  is  round ;  as  its  name 
imports.  It  is  situated  immediately  under  the  foramen  lacerum, 
on  each  side,  and  transmits  the  second  branch  of  the  fifth  pair 
of  nerves  to  the  upper  maxillary  bone. 

The  foramen  ovale  is  the  fourth  hole.  It  is  larger  than  the 
foramen  rotundum,  and  half  an  inch  behind  it.  It  transmits  the 
third  branch  of  the  fifth  pair  of  nerves  to  the  lower  jaw. 

The  fifth  hole  is  the  foramen  spinale.  It  is  small  and  round, 
and  placed  in  the  point  of  the  spinous  process,  behind  the  fora- 
men ovale,  to  transmit  the  principal  artery  of  the  dura  mater, 
which  makes  its  impression  upon  the  parietal  bone. 


THE    fACE.  85 

The  sixth  foramen  is  under  the  basis  of  each  pterygoid 
process,  and  is  therefore  called  the  pterygoid,  or  the  Vidian* 
foramen.  It  is  almost  hidden  by  the  point  of  the  petrous 
portion  of  the  temporal  bone,  and  must  be  examined  m  the 
separated  bone.  It  is  nearly  equal  in  size  to  the  spinous 
hole. 

This  foramen  transmits  a  nerve  that  does  not  go  out  from 
the  cavity  of  the  skull,  but  returns  into  it.  The  second  branch 
of  the  fifth  pair,  after  passing  out  of  the  cranium,  sends  back, 
through  this  foramen,  a  branch  called  the  Vidian,  which  upon 
its  arrival  in  the  cavity  of  the  cranium,  enters  the  temporal  bone 
by  the  foramen  innominatum. 


Of  the  Face. 

The  face  is  the  irregular  pile  of  bones  composing  the  front 
and  under  part  of  the  head,  and  is  divided  into  the  upper  and 
lower  maxillae,  or  jaws. 

The  upper  jaw  consists  of  six  bones  on  each  side,  of  one 
single  bone  placed  in  the  middle,  and  of  sixteen  teeth. 

The  thirteen  bones  are,  two  ossa  maxillaria  superiora,  two 
ossa  nasi,  two  ossa  unguis,  two  ossa  malarum,  two  ossa  palati, 
two  ossa  spongiosa  inferiora,  and  the  vomer. 

The  ossa  maxillaria  superiora  form  the  principal  part  of  the 
cavity  of  the  nose,  with  the  whole  lower  and  forepart  of  the 
upper  jaw,  and  a  large  proportion  of  the  roof  of  the  mouth. 

The  ossa  nasi  are  placed  at  the  upper  and  front  part  of  the 
nose. 

The  ossa  unguis  are  at  the  internal  angles  of  the  orbits  of 
the  eyes. 

The  ossrt  palati  in  the  back  part  of  the  palate,  extending 
upwards  to  the  orbits  of  the  eyes. 

The  ossa  spongiosa  in  the  lower  part  of  the  cavity  of  the 
nose  ;  and 

The  vomer  in  the  partition  which  separates  the  two  nostrils. 

*  From  its  reputed  discoverer,  Vidius,  a  professor  at  Paris, 
8 


86  OSSA  MAXILLARIA  SUPERIORA. 

Ossa  Maocillaria  Superiora. 

The  ossa  maxillaria  superiora,  or  upper  jaw  bones,  may  be 
considered  as  the  basis  or  foundation  of  the  face ;  as  they  form 
a  large  part  of  the  mouth,  the  nose,  and  the  orbit  of  the  eye. 

The  central  part  of  each  bone,  which  may  be  considered  as 
its  body,  is  hollow,  and  capable  of  containing,  in  the  adult, 
near  half  an  ounce  of  fluid.  .  The  plate  which  covers  this 
cavity  is  the  bottom  of  the  orbit  of  the  eye.  The  sockets  of 
the  large  teeth  are  below  it.  The  roof  of  the  mouth  projects 
laterally  from  the  inside  of  it.  A  process  for  supporting  the 
cheek  bone  is  on  the  outside  ;  and  another  process  goes  up 
before  it,  which  forms  the  side  of  the  nose. 

Fig.  20.*  In  each  upper  maxillary  bone  the  fol- 

lowing parts  are  to  be  examined  : 

The  nasal  process ;  the  orbitar  plate  ; 
the  malar  process  ;  the  alveolar  process  ; 
the  palatine  process ;  the  anterior  and 
posterior  surfaces ;  the  great  cavity ;  the 
internal  or  nasal  surface  ;  and  the  three 
foramina. 

The  nasal  process,  which  extends 
upwards  to  form  the  side  of  the  nose, 
is  rather  convex  outwards,  to  give  the 
nostril  shape.  Its  sides  above  support 
the  nasal  bone ;  and  a  cartilage  of  the 
alae  nasi  is  fixed  to  its  edge  below. 

The  margin  of  the  orbit  of  the  eye  is  marked  by  a  sharp 
ridge  on  the  external  surface  of  this  process ;  and  the  part 

*  The  superior  maxillary  bone  of  the  right  side,  as  seen  from  the  lateral 
aspect.  1.  The  external,  or  facial  surface  ;  the  depression  in  which  the  figure 
is  placed  is  the  canine  fossa.  2.  The  posterior,  or  zygomatic  surface.  3.  The 
superior,  or  orbital  plate  or  surface.  4.  The  infra-orbital  foramen :  it  is  situated 
immediately  below  the  number.  5.  The  infra-orbital  canal,  leading  to  the  infra- 
orbital  foramen.  6.  The  inferior  border  of  the  orbit.  7.  The  malar  process. 
8.  The  nasal  process.  9.  The  concavity  forming  the  lateral  boundary  of  the 
anterior  nares.  10.  The  nasal  spine.  11.  The  incisive,  or  myrtiform  fossa. 
12.  The  alveolar  process.  13.  The  internal  border  of  the  orbital  surface,  which 
articulates  with  the  ethmoid  and  palate  bones.  14.  The  concavity  which  articu- 
lates with  the  lachrymal  bone,  and  forms  the  commencement  of  the  nasal  duct. 
15.  The  palate  process,  t.  The  two  incisor  teeth,  c.  The  canine,  b.  The  two 
bicuspidati.  m.  The  three  molares. 


OSSA  MAXILLARIA    SUPERIORA.  87 

posterior  to  this  ridge  is  concave  to  accommodate  the  lachrymal 
sac. 

The  orbitar  plate,  which  covers  the  great  cavity,  and  forms 
the  bottom  of  the  orbit,  is  rather  triangular  in  form,  arid  con- 
cave. In  the  posterior  part  is  a  groove  or  canal,  which  pene- 
trates the  substance  of  the  bone,  as  it  advances  forward,  and 
terminates  in  the  infra-orbitary  foramen,  below  the  orbit.  At 
the  place  where  this  plate  joins  the  nasal  process  above  men- 
tioned, viz.  at  the  inner  angle  of  the  orbit,  is  the  commencement 
of  the  bony  canal,  which  transmits  the  lachrymal  duct  into  the 
cavity  of  the  nose. 

The  malar  process  projects  from  the  external  and  anterior 
corner  of  the  orbitar  plate ;  it  supports  the  malar  bone,  and  is 
rough  for  the  purpose  of  articulating  with  it. 

The  alveolar  processes  compose  the  inferior  and  external 
margins  of  the  upper  maxillary  bones.  When  these  bones 
are  applied  to  each  other,  they  form  more  than  a  semicircle : 
their  cavities  contain  the  roots  of  the  teeth,  and  correspond 
with  them  in  size  and  form.  They  do  not  exist  long  before 
the  formation  of  the  teeth  commences  ;  they  grow  with  the 
teeth  ;  and  when  these  bodies  are  removed,  the  alveoli  dis- 
appear. 

The  palate  process  is  a  plate  of  bone,  which  divides  the  nose 
from  the  mouth,  constituting  the  roof  of  the  palate,  and  the  floor 
or  bottom  of  the  nostrils.  It  is  thick  where  it  first  comes  off 
from  the  alveolar  process  ;  it  is  thin  in  its  middle  ;  and  it  is 
again  thick  where  it  meets  its  fellow  of  the  opposite  side.  At 
the  place  where  the  two  upper  jaw  bones  meet,  the  palate  plate 
is  turned  upwards,  so  that  the  two  bones  are  opposed  to  each 
other  in  the  middle  of  the  palate,  by  a  broad  flat  surface,  which 
cannot  be  seen  but  by  separating  the  bones.  This  surface  is  so 
very  rough,  that  the  middle  palate  suture  almost  resembles  the 
sutures  of  the  skull ;  and  the  maxillary  bones  are  neither  easily 
separated,  nor  easily  joined  again.  The  meeting  of  the  palate 
plates  by  a  broad  surface,  makes  a  rising,  or  sharp  ridge, 
towards  the  nostrils  ;  so  that  the  breadth  of  the  surface  by 
which  these  bones  meet,  serves  a  double  purpose  ;  it  joins  the 


88  OSSA  MAXILLARIA  SUPERIORA. 

bones  securely,  and  it  forms  a  small  ridge  upon  which  the  edge 
of  the  vomer,  or  partition  of  the  nose,  is  planted.  Thus  we 
find  the  palate  plates  of  the  maxillary  bones  conjoined,  forming 
almost  the  whole  of  the  palate ;  while  what  properly  belongs  to 
the  palate  bones  forms  a  very  small  share  of  the  back  part  only, 

As  these  thinner  bones  of  the  face  have  no  medulla,  they  are 
nourished  by  their  periosteum  only,  and  are  of  course  perforated 
with  many  small  holes. 

The  anterior,  external  or  facial  surface  of  the  upper  maxil- 
lary bone  is  concave  ;  the  margin  formed  by  the  lower  edge  of 
the  orbit,  by  the  malar  process,  and  by  the  alveolar  processes, 
being  more  elevated  than  the  central  part,  which  consists  of  a 
depression  called  \\\Q  fossa  canina,  which  gives  attachment  to 
two  muscles,  the  compressor  nasi,  and  levator  anguli  oris.  At 
a  small  distance  below  the  orbit  is  the  infra-orbitary  foramen 
for  transmitting  a  branch  of  the  superior  maxillary  nerve. 
When  these  two  bones  are  applied  to  each  other,  and  the  ossa 
nasi  are  in  their  places,  they  form  the  anterior  orifice  of  the 
nasal  cavity,  which  has  a  small  resemblance  to  the  inverted 
figure  of  the  heart  on  cards. — The  concave  border  of  the  open- 
ing of  the  nostrils,  is  projected  forwards  at  its  lower  surface 
into  a  sharp  process,  forming  with  a  similar  process  at  the  oppo- 
site side  the  nasal  spine.  Beneath  the  nasal  spine,  and  above 
the  two  superior  incisor  teeth,  is  a  slight  depression  called  the 
incisive  or  myrtiform  fossa,  which  gives  origin  to  the  depressor 
labii  superioris  alaeque  nasi  muscle — . 

The  posterior  zygomatic  surface  has  been  called  a  process 
or  tuber.  The  tuberosity  is  pierced  by  a  number  of  small 
foramina,  giving  passage  to  the  posterior  dental  nerves,  and 
branches  of  the  superior  dental  artery.  It  expands  to  a  con- 
siderable size,  and  is  united  internally  and  posteriorly  to  the  ossa 
palati.  The  great  cavity  extends  from  the  bottom  of  the  orbit 
of  the  eye  to  the  roof  of  the  mouth,  and  from  the  anterior  to 
the  posterior  surface  of  the  bone  ;  it  opens  in  the  cavity  of 
the  nose,  and  is  called  antrum  maxillare,  or  Highmorianum.* 
There  is  but  a  small  portion  of  bone  between  this  cavity 

*  After  an  anatomist  who  described  it. 


OSSA    NASI.  89 

and  the  sockets  of  the  teeth,  particularly  those  of  the  second 
molar  tooth  ;  occasionally  the  fangs  of  the  tooth  enter  the  cavity. 

The  internal  or  nasal  surface  of  this  bone  forms  a  large  part 
of  the  cavity  of  the  nose,  and  is  concave.  At  the  roof  of  the 
nasal  process  is  a  ridge,  for  supporting  the  anterior  end  of  the 
lower  turbinated  bone.  The  nasal  process  seems  continued 
into  the  cavity  of  the  nose,  and  forms  a  portion  of  the  orifice 
of  the  canal  for  the  lachrymal  duct,  which  is  on  the  external 
side  of  this  cavity,  near  its  anterior  opening,  and  under  the 
lower  furbinated  bone.  The  orifice  in  this  bone  by  which  the 
antrum  maxillare  communicates  with  the  nose,  is  very  large ; 
but  it  is  reduced  to  a  small  size,  by  a  plate  from  the  ethmoid 
bone,  by  a  portion  of  the  os  palati,  and  of  the  lower  spongy 
bone,  each  of  which  covers  a  part  of  it. 

The  three  foramina  are,  1st.  The  infra-orbitary  foramen 
already  described.  2d.  The  foramen  incisivum  or  anterior 
palatine  hole,  which  passes  through  the  palatine  process,  from 
the  nose  to  the  mouth.  In  the  nose  it  forms  generally  two 
foramina,  which  unite  and  form  but  one  in  the  mouth,  imme- 
diately behind  the  middle  incisor  teeth.  This  foramen  is 
closed  by  the  soft  parts  during  life,  and  transmits  a  branch  of 
the  spheno-palatine  nerve  from  each  side,  which  runs  on  the 
septum  narium,  and  joining  at  the  lower  part  of  the  canal  with 
its  fellow,  they  unite,  and,  according  to  M.  Cloquet,*  form  a 
ganglion.  3d.  The  posterior  palatine  foramen,  which  is  formed 
by  this  bone,  and  by  the  os  palati,  on  each  side,  is  situated  in 
the  suture  which  joins  them  to  each  other,  and  transmits  to  the 
palate  a  branch  of  the  upper  maxillary  nerve. 

This  bone  is  united  to  the  frontal,  nasal,  unguiform,  ethmoid 
and  malar  bones,  above  ;  to  the  ossa  palati  behind  ;  to  the  cor- 
responding bone,  on  the  opposite  side  ;  and  to  the  inferior  spongy 
bone,  in  the  cavity  of  the  nose. 

Ossa  Nasi. 
The  ossa  nasi  are  so  named  from  their  prominent  situation 

*  This  ganglion,  though  it  varies  in  size,  is  readily  found.    I  always  exhibit 
it  in  the  course  of  my  lectures. — p. 

8* 


90  OSSA    UNGUIS. 

at  the  root  of  the  nose.  They  are  each  of  an  irregular  oblong 
figure,  being  broadest  at  their  lower  end,  narrowest  near  the 
middle,  and  larger  again  at  the  top,  where  the  edge  is  rough 
and  thick,  and  their  connexion  with  the  os  frontis  is  conse- 
quently very  strong.  They  are  convex  externally,  and  concave 
within.  The  lower  edges  of  these  bones  are  thin  and  irregular. 
Their  anterior  edges  are  thick,  and  their  connection  with  each 
other,  by  means  of  their  edges,  is  firm ;  the  suture  between 
them,  extending  down  the  middle  of  the  nose,  forms  a  promi- 
nent line  on  the  internal  surface,  by  which  they  are  united  to 
the  septum  narium.  The  uppermost  half  of  their  posterior 
edges  is  covered  by  the  edges  of  the  nasal  processes  of  the 
upper  maxillary  bones ;  the  lower  half  laps  over  the  edges  of 
these  bones  ;  and  by  this  structure  they  are  enabled  to  resist 
pressure.  [On  the  posterior  surface  of  the  os  nasi  is  a  groove 
occupied  in  the  recent  subject  by  a  branch  of  the  ophthalmic 
nerve  called  the  nasal,  which  enters  the  nose  through  the  fora- 
men orbitare  internum  anterius.]  They  are  joined  above  to  the 
os  frontis ;  before,  to  each  other ;  behind,  to  the  upper  maxillary 
bones  ;  below,  to  the  cartilages  ;  and  internally,  to  the  septum  of 
the  nose. 

Ossa  Unguis,  or   Ossa  Lachrymalia. 

The  ossa  unguis  are  so  named  from  their  resemblance  to  a 
nail  of  the  finger.  They  are  situated  on  the  internal  side  of  the 
orbit  of  the  eye,  between  the  os  planum  of  the  ethmoid,  and 
the  nasal  process  of  the  upper  maxillary  bone.  Their  external 
surface  is  divided  into  two  portions,  by  a  middle  ridge ;  the 
posterior  portion  forms  part  of  the  orbit ;  and  the  anterior,  which 
is  very  concave,  forms  part  of  the  fossa  and  canal,  for  contain- 
ing the  lachrymal  sac  and  duct.  This  portion  is  perforated 
by  many  small  foramina  ;  and  the  whole,  being  extremely  thin 
and  brittle,  is  therefore  often  destroyed  by  the  preparation  of  the 
subject. 

The  internal  surface  of  this  bone  is  generally  in  contact  with 
the  cells  of  the  ethmoid  ;  a  small  portion  of  the  anterior  parts  is 
in  the  general  cavity  of  the  nose.  Each  os  unguis  is  joined 


OSSA    MALARUM.  91 

above  to  the  frontal  bone ;  behind  to  the   os   planum  ;  before 

and  below  to   the  maxillary  bone.  It  sometimes  is  extended 

into  the   nose,  as  low  as  the  upper  edge  of  the  inferior  spongy 
bone. 

Ossa  Malarum. 

The  ossa  malarum  are  the  prominent  square  bones  which 
form  the  cheek,  on  each  side.  Before,  their  surface  is  convex 
and  smooth ;  backward,  it  is  unequal  and  concave,  for  lodging 
part  of  the  temporal  muscles. 

The  four  angles  of  each  of  these  bones  have  been  reckoned 
as  processes.  The  one  at  the  external  canthus  of  the  orbit 
called  the  superior  orbitar  process,  is  the  longest  and  thickest, 
The  second  terminates  near  the  middle  of  the  lower  edge  of 
the  orbit  in  a  sharp  point,  and  is  named  the  inferior  orbitar 
process.  The  third,  placed  near  the  lower  part  of  the  cheek, 
and  thence  called  maxillary,  is  the  shortest  and  nearest  to  a 
right  angle.  The  fourth,  which  is  called  zygomatic,  because  it 
is  extended  backwards  to  the  zygoma  of  the  temporal  bone, 
ends  in  a  point,  and,  has  one  side  straight  and  the  other  sloping. 
Between  the  two  orbitar  angles  there  is  a  concave  arch,  which 
makes  about  a  third  of  the  external  circumference  of  the  orbit, 
from  which  a  fifth  process  is  extended  backwards  within  the 
orbit,  to  form  near  one-sixth  of  that  cavity ;  and  hence  it  may 
be  called  the  internal  orbitar  process.  From  the  lower  edge 
of  each  of  the  ossa  malarum,  which  is  between  the  maxillary 
and  zygomatic  processes,  the  masseter  muscle  takes  its  origin. 

On  the  external  surface  of  each  cheek  bone,  one  or  more 
small  holes  are  commonly  found  for  the  transmission  of  small 
nerves  or  blood-vessels  from,  and  sometimes,  into  the  orbit. 
On  the  internal  surface  are  the  holes  for  the  passage  of  the 
nutritious  vessels  of  these  bones.  A  notch,  on  the  outside  of 
the  internal  orbitar  process  of  each  of  these  bones,  assists  to 
form  the  great  slit  common  to  this  bone,  and  to  the  sphenoid, 
maxillary,  and  palate  bones. 

The  substance  of  these  bones  is,  in  proportion  to  their  bulk, 
thick,  hard,  and  solid,  with  some  cancelli. 


92  OSSA   PALATI. 

Each  of  the  ossa  malarum  is  joined,  by  its  superior  and 
internal  orbitar  processes,  to  the  os  frontis,  and  the  orbitar 
process  of  the  sphenoid  bone;  by  the  edge  between  the  internal 
and  inferior  orbitar  processes,  to  the  maxillary  bone  ;  by  the 
side  between  the  maxillary  and  inferior  orbitar  process,  again 
to  the  maxillary  bone ;  and  by  the  zygomatic  process  to  the  os 
temporis. 

Ossa  Palati. 

The  ossa  palati  form  the  back  part  of  the  roof  of  the  mouth, 
and  extends  from  it  along  the  external  sides  of  the  posterior 
openings  of  the  nose,  into  the  orbits  of  the  eyes.  Each  bone 
may  therefore  be  divided  into  four  parts,  the  palate  square  bone, 
or  palatine,  or  horizontal  process,  the  pterygoid  process  or 
tuberosity,  the  nasal  lamella  or  perpendicular  plate,  and  the 
orbitar  process. 

The  square  bone  is  irregularly  concave,  for  enlarging  both 
the  mouth  and  cavity  of  the  nose.  The  upper  part  of  its 
internal  edge  rises  in  a  spine,  after  the  same  manner  as  the 
palate  plate  of  the  maxillary  bone  does,  to  be  joined  with  the 
vomer.  Its  anterior  edge  is  unequally  ragged,  for  its  firmer 
connexion  with  the  palate  process  of  the  os  maxillare.  The 
internal  edge  is  thicker  than  the  rest,  and  of  an  equal  surface. 
for  its  conjunction  with  its  fellow  of  the  other  side.  Behind, 
this  bone  is  somewhat  in  form  of  a  crescent,  and  thick,  for  the 
firm  connexion  of  the  velum  pendulum  palati ;  the  internal 
point  being  extended  backwards,  to  afford  origin  to  the  palato- 
staphylinus  or  azygos  muscle.  This  square  bone  is  well  dis- 
tinguished from  the  pterygoid  process  by  a  perpendicular  fossa, 
which,  applied  to  a  similar  one  in  the  maxillary  bone,  forms  a 
passage  (ptery go-maxillary)  for  the  palatine  branch  of  the  fifth 
pair  of  nerves ;  and  by  another  small  hole  behind  this,  through 
which  a  twig  of  the  same  nerve  passes. 

The  pterygoid  process  is  somewhat  triangular,  having  a 
broad  base,  and  ending  smaller  above.  The  back  part  of  this 
process  has  three  fossae  formed  in  it ;  the  two  lateral  receive 
the  ends  of  the  two  pterygoid  plates  of  the  sphenoid  bone ;  the 


OSSA    PALATI.  93 

Fig.  20.*  middle    fossa,   which    is    very    superficial, 

makes  up  a  part  of  what  is  commonly 
called  the  fossa pterygoidca.  The  foreside 
of  this  pterygoid  process  is  rotf^h  and 
irregular  where  it  joins  the  back  part  of 
the  great  tuberosity  of  the  maxillary  bone. 
Frequently  several  small  holes  may  be 
observed  in  this  triangular  process,  par- 
ticularly one  near  the  middle  of  its  base, 
which  a  little  above  communicates  with 
the  common  and  proper  holes  of  this  bone 
already  mentioned. 

The  nasal  lamella  of  this  bone  is  extremely  thin  and  brittle, 
and  rises  upwards  from  the  upper  side  of  the  external  edge  of 
the  square  bone,  and  from  the  narrow  extremity  of  the  ptery- 
goid process ;  it  is  so  weak,  and,  at  the  same  time,  so  firmly 
fixed  to  the  maxillary  bone,  as  to  be  very  liable  to  be  broken 
in  separating  the  bones.  From  the  part  where  the  plate  rises, 
it  runs  up  broad  on  the  inside  of  the  tuberosity  of  the  maxillary 
bone,  to  form  a  considerable  share  of  the  sides  of  the  maxillary 
sinus,  and  to  close  up  the  space  between  the  sphenoid  and  the 
great  bulge  of  the  maxillary  bone,  where  there  would  other- 
wise be  a  large  slit  opening  into  the  nostrils.  On  the  middle 
of  the  internal  side  of  this  thin  plate,  there  is  a  transverse  ridge, 
continued  from  one  which  is  similar  to  it  in  the  maxillary  bone 

*  A  posterior  view  of  the  palate  bone  in  its  natural  position  ;  it  is  slightly 
turned  to  one  side  to  obtain  a  view  of  the  internal  surface  of  the  perpendicular 
plate  (2).  1.  The  horizontal  plate  of  the  bone;  its  upper  or  nasal  surface. 

2.  The  perpendicular  plate  or  nasal  lamella,  seen  on  its  internal  or  nasal  surface. 

3,  10,  11.  The  pterygoid  process  or  tuberosity.     4.  The  broad  internal  border  of 
the  horizontal  or  palatine  process,  which  articulates  with  the  similar  process  of 
the  bone  of  the  other  side.     5.  The  ridge  which  with  a  similar  elevation  of  the 
opposite  bone  forms  the  palate  spine.     6.  The  horizontal  ridge  which  gives 
attachment  to  the  inferior  turbinated  bone ;  the  concavity  below  this  ridge  forms 
a  part  of  the  inferior  meatus  of  the  nose,  and  the  concavity  (2)  above  the  ridge 
forms  a  part  of  the  middle  and  superior  meatus.     7.  The  spheno-palatine  fora- 
men.    8.  The  orbital  process  of  the  bone.     10.  The  middle  facet  of  the  ptery- 
goid process  or  tuberosity  which  forms  the  middle  of  the  pterygoid  fossa.     The 
fossae  11  and  3,  articulate  with  the  two  pterygoid  plates  of  the  sphenoid  bone: 
11  with  the  internal,  and  3  with  the  external. 


94 


OSSA   PALATI. 


for  supporting  the  back  part  of  the  os  spongiosum  inferius. 
Along  the  outside  of  this  plate,  the  perpendicular  fossa  made 
by  the  posterior  palatine  nerve  is  observable. 

At  the  upper  and  posterior  edge  of  this  nasal  plate  is  a  notch, 
which  when  applied  to  the  sphenoid  bone,  forms  the  spheno- 
palatine  foramen,  through  which  a  nerve,  artery,  and  vein  pass 
to  the  nostril ;  this  notch  forms  two  processes  on  the  posterior 
part  of  the  bone,  the  inferior  of  which  is  in  contact  with  the 
internal  plate  of  the  pterygoid  process  of  the  sphenoidal  bone, 
and  has,  therefore,  been  called  by  some  French  anatomists,  the 
pterygoid  apophysisofthe  ospalati.  The  superior  and  anterior 
portion  is  the  proper  orbitar  process  of  this  bone,  which  is 
Fig.  21.*  situated  at  the  posterior  part  of  the  lower 
surface  of  the  orbit,  and  forms  a  portion 
of  it.  This  process  of  the  os  palati  is 
hollow ;  and  its  cavity  generally  com- 
municates with  the  contiguous  cell  of  the 
os  ethmoides.  It  has  several  surfaces, 
one  of  which  is  to  be  found  in  the  orbit, 
and  another  in  the  zygomatic  fossa. 

The  palate  square   part  of  the   palate 
bone,  and  its  pterygoid  process,  are  firm 
and  strong,  with  some  cancelli ;  but  the 
nasal  plate,  and  orbitar  processes,  are  very  thin  and  brittle. 

The  palate  bones  are  joined  to  the  maxillary,  by  the  fore 
edges  of  the  palate  square  bones  ;  by  their  thin  nasal  plates, 
and  part  of  their  orbitary  processes,  to  the  same  bones  ;  by 
their  pterygoid  processes,  and  back  part  of  the  nasal  plates,  to 


*  The  perpendicular  plate  of  the  palate  bone  seen  upon  its  external  or  spheno- 
maxillary  surface.  1.  The  rough  surface  of  this  plate,  which  articulates  with 
the  superior  maxillary  bone.  2.  The  posterior  palatine  canal,  completed  by  the 
tuberosity  of  the  superior  maxillary  bone.  The  rough  surface  to  the  left  of  the 
canal  (2)  articulates  with  the  internal  pterygoid  plate.  3.  The  spheno-palatine 
or  lateral  nasal  foramen.  4,  5,  6.  The  orbital  portion  of  the  perpendicular  plate. 
4.  The  pterygoid  apophysis  or  spheno-maxillary  facet  of  this  portion.  5.  Its 
orbital  facet  or  process.  6.  Its  maxillary  facet,  to  articulate  with  the  superior 
maxillary  bone.  7.  The  sphenoidal  portion  of  the  perpendicular  plate.  8.  The 
pterygoid  process  or  tuberosity  of  the  bone. 


OSSA  SPONGIOSA  INFERIORA. THE  VOMER.  95 

the  pterygoid  processes  of  the  os  sphenoides  ;  by  the  transverse 
ridges  of  their  nasal  lamellae  to  the  ossa  turbinata  inferiora,  and 
by  the  spines  of  the  square  bones  to  the  vomer.  *j 

j/n 

The  Ossa  Spongiosa,  or  Turbinata  Inferiora. 

The  ossa  spongiosa,  or  turbinata  inferiora,  are  so  named  to 
distinguish  them  from  the  upper  spongy  bones,  which  belong 
to  the  os  ethmoides  ;  but  these  lower  spongy  bones  are  quite 
distinct,  and  connected  in  a  very  slight  way  with  the  upper 
jaw  bones.  They  are  rolled  or  convoluted,  very  spongy,  and 
exceedingly  light.  Each  of  them  is  attached  to  the  os  maxil- 
lare  superius,  near  the  transverse  ridge,  by  a  hook-like  process, 
and  covers  a  part  of  the  opening  of  the  maxillary  sinus.  One 
end  is  turned  towards  the  anterior  opening  of  the  nose,  and 
covers  the  end  of  the  lachrymal  duct ;  the  other  end  of  the  same 
bone  points  backwards  towards  the  throat.  The  curling  plate 
hangs  down  into  the  cavity  of  the  nostril,  with  its  convex  side 
towards  the  septum.  This  spongy  bone  differs  from  the  spongy 
processes  of  the  ethmoid  bone,  in  being  less  turbinated  or 
complex,  and  in  having  no  cells  connected  with  it. 

The  Vomer. 

The  vomer  is  a  thin  flat  bone,  which  forms  the  back  part  of 
the  septum  of  the  nose.  Its  posterior  edge  extends  downwards 
from  the  body  of  the  os  sphenoides  to  the  palatine  processes  of 
the  ossa  palati,  separating  the  posterior  nares  from  each  other. 

The  figure  of  this  bone  is  an  irregular  rhomboid.  Its  sides 
are  smooth ;  and  its  posterior  edge  appears  in  an  oblique 
direction  at  the  back  part  of  the  nostrils.  The  upper  edge  is 
firmly  united  to  the  base  of  the  sphenoid  bone,  and  to  the  nasal 
plate  of  the  ethmoid.  It  is  hollow  for  receiving  the  processus 
azygos  of  the  sphenoid,  and  where  it  is  articulated  to  the  nasal 
plate  of  the  ethmoid,  it  is  composed  of  two  lamina  which 
receive  this  plate  between  them.  The  anterior  edge  has  a 
long  furrow  in  it,  where  the  middle  cartilage  of  the  nose  enters. 
The  lower  edge  is  firmly  united  to  the  nasal  spines  of  the 
.-, 


96  MAXILLA  INFERIOR. 

maxillary  and  palate  bone.  These  edges  of  the  bone  are  much 
thicker  than  its  middle,  which  is  as  thin  as  paper ;  in  conse- 
quence of  which,  and  of  the  firm  union  or  connexion  this  bone 
has  above  and  below,  it  can  very  seldom  be  separated  entire  in 
adults ;  but  in  a  child  it  is  much  more  easily  separated  entire, 
and  its  structure  is  more  distinctly  seen. 

Its  situation  is  not  always  perpendicular,  but  often  inclined 
and  bent  to  one  side,  as  well  as  the  nasal  plate  of  the  ethmoid 
bone. 

It  is  united  above  to  the  os  sphenoides  and  the  nasal  plate 
of  the  ethmoid  bone  ;  before  to  the  middle  cartilage  of  the 
nose ;  and  below,  to  the  ossa  palati  and  ossa  maxillaria  supe- 
riora. 

Maxilla  Inferior,  or  Lower  Jaw. 

The  form  and  situation  of  this  bone  are  so  generally  known, 
that  they  do  not  require  description.  To  acquire  an  accurate 
idea  of  the  lower  jaw,  it  is,  however,  necessary  to  examine 
attentively  its  different  parts :  viz.  the  chin,  or  mental  protuber- 
ance, the  sides,  the  angles,  and  the  processes. 

In  subjects  where  the  bones  are  strongly  marked,  there 
is  a  prominent  vertical  ridge  in  the  middle  and  most  inferior 
part  of  the  chin  which  becomes  broad  below  so  as  to  form  a 
triangle,  and  on  each  side  of  this  triangular  prominence  are 
transverse  ridges  ;  from  these  eminences  the  muscles  of  the  lower 
lip  originate. 

On  each  side  of  the  jaw,  commonly  under  the  second  of  the 
bicuspides,  or  small  molar  teeth,  is  the  anterior  maxillary  or 
mental  foramen,  through  which  pass  out  branches  of  the 
inferior  maxillary  nerve  and  blood-vessels.^  This  foramen, 
has  a  direction  upward  and  backward.  At  a  ?mall  distance 
behind  these  foramina,  on  each  side,  is  the  commencement  of  a 
ridge  which  continues  backward  until  it  forms  the  edge  of  the 
anterior  or  coronoid  process.  The  alveolar  processes,  which 
form  the  upper  edge  of  the  jaw,  are  on  the  inside  of  this  ridge ; 
the  alveoli  or  sockets  corresponding  with  the  roots  of  the  teeth, 
in  number  and  form.  The  lower  edge  of  the  jaw,  which  is 


7^ 


: 


MAXILLA  INFERIOR.  97 

denominated  the  base,  is  round  and  firm,  except  at  the  angles, 
where  it  is  thin. 

The  angle  is  formed  at  the  posterior  extremity  of  the  base  : 
in  children  it  is  obtuse ;  but  in  adults  whose  teeth  are  perfect, 
it  is  nearly  rectangular.  The  masseter  muscle  is  inserted  into 
the  lower  jaw,  at  the  angle ;  and  there  are  several  inequalities 
on  the  surface  made  by  this  muscle. 

Fig.  22.*  The    anterior  or   coronoid 

process,  is  rather  higher  than 
the  posterior,  and  forms  an 
obtuse  point :  into  this  process 
the  temporal  muscle  is  inserted. 
The  anterior  edge  of  the  coro- 
noid process  is  sharp,  and  con- 
tinued into  the  rid^e  above 

O 

mentioned  ;  from  this  edge  the 
buccinator  muscle  arises.  As 
the  alveoli  are  on  the  inside  of 
this  edge  and  ridge,  the  jaw  is  very  thick  at  this  place.  There 
is  a  semicircular  or  sigmoid  notch  between  this  coronoid  process 
and  the  posterior  or  condyloid ;  and  here  the  bone  is  very  thin. 

The  condyles  are  oblong,  and  are  placed  obliquely ;  so  that 
their  longest  axes,  if  extended  until  they  intersect  each  other, 
would  form  an  angle  of  more  than  one  hundred  and  forty 
degrees.  The  neck  of  the  process,  or  the  part  immediately 
below  the  condyle,  is  concave  on  the  anterior,  arid  convex  on 
the  posterior  surface. 

On  the  inside  of  the  jaw,  in  the  middle  of  the  chin,  is  a  small 
protuberance,  sometimes  divided  by  a  vertical  fissure  ;  to  this 
are  attached  the  fraenum  lingua,  and  some  muscles  of  the 
tongue  and  os  hyoides.  Farther  back  is  a  ridge  called  the 
mylo-hyoid,  which  extends  backwards  and  upwards,  until  it 

*  The  lower  jaw.  1.  The  body.  2.  The  ramus.  3.  Thesymphysis.  4.  The 
fossa  for  the  depressor  labii  inferioris  muscle.  5.  The  mental  foramen.  6.  The 
external  oblique  ridge.  7.  The  groove  for  the  facial  artery.  8.  The  angle.  9. 
The  extremity  of  the  mylo-hyoidean  ridge.  10.  The  coronoid  process.  11.  The 
condyle.  12.  The  sigmoid  notch.  13.  The  inferior  dental  foramen.  14.  The 
mylo-hyoidean  groove.  15.  The  alveolar  process.  ».  The  middle  and  lateral 
incisor  tooth  of  one  side.  c.  The  canine  tooth,  b.  The  two  bicuspides.  m.  The 
three  molares. 

9 


98  MAXILLA  INFERIOR. 

approaches  the  alveoli  of  the  last  molar  teeth ;  where  it  termi- 
nates in  an  oblong  protuberance.  To  the  anterior  part  of  this 
line  the  mylo-hyoidei  muscles  are  attached  ;  and  to  the  posterior 
extremity,  the  superior  constrictor  of  the  pharynx.  The  surface 
of  the  bone  above  this  ridge  is  smooth,  and  covered  with  the 
gums  and  lining  membrane  of  the  mouth.  The  surface  below 
the  posterior  part  of  the  line  is  rather  concave,  to  accommodate 
the  submaxillary  gland. 

At  a  small  distance  behind  the  alveoli,  and  nearly  on  a  line 
with  them,  midway  between  the  roots  of  the  two  processes,  is 
a  large  foramen,  called  the  inferior  dental,  for  transmitting  the 
third,  or  inferior  maxillary  branch  of  the  fifth  pair  of  nerves, 
and  the  blood-vessels  which  accompany  it ;  the  canal,  which 
commences  here,  terminates  at  the  anterior  foramen,  already 
described.*  The  surface  of  this  canal  is  perforated  by  many 
foramina,  through  which  blood-vessels  and  nerves  pass  to  the 
different  teeth,  and  to  the  cancelli  of  the  bone.  On  the  anterior 
side  of  the  foramen  is  a  sharp-pointed  process,  from  which  a 
ligament  passes  to  the  temporal  bone.  The  nerve  and  vessels, 
before  they  enter  into  this  foramen,  make  an  impression  on  the 
bone ;  and  there  is  generally  a  small  superficial  groove  called 
the  mylo-Jiyoid,  which  proceeds  downwards  from  it,  being  made  by 
a  small  nerve  which  supplies  some  of  the  parts  under  the  tongue. 

At  the  angle  of  the  jaw,  on  the  inside,  is  a  remarkable  rough- 
ness, where  the  internal  pterygoid  muscle  is  inserted. 

The  lower  jaw  moves  like  a  hinge  upon  its  condyles  in  the 
glenoid  cavity,  when  the  mouth  opens  and  shuts  in  the  ordinary 
way.  When  the  mouth  is  opened  very  wide,  the  condyles  move 
forward  upon  the  tubercles  before  the  cavities :  if  the  effort  to 
open  the  mouth  is  continued,  the  lower  jaw  is  fixed  in  that 
situation,  and  the  whole  head  is  thrown  back,  which  separates 
the  upper  jaw  still  farther  from  the  lower. 

The  lower  jaw  can  be  projected  forward  without  opening  the 
mouth,  by  the  movement  of  both  condyles,  at  the  same  time,  on 
the  tubercles. 

This  bone  can  also  rotate  upon  one  condyle,  as  a  centre,  while 

*  A  branch  of  this  canal  is  continued  forwards  to  the  symphysis  by  which 
the  front  teeth  are  supplied  with  vessels  and  nerves.— p. 


THE  TEETH. 


99 


the  other  moves  out  of  the  glenoid  cavity,  upon  the  tubercle : 
but  these  important  motions  can  be  better  understood,  after  the 
muscles,  and  the  articulation  with  the  temporal  bone,  in  its  recent 
state,  have  been  described. 

Fig.  23. 


Of  the   Teeth. 

In  the  adult,  when  the  teeth  are  perfect,  there  are  sixteen  in 
each  jaw,  and  those  in  corresponding  situations,  on  the  opposite 
sides,  resemble  each  other  exactly. 

They  are  of  four  kinds,  viz.  incisores,  or  the  fore  teeth  ;  cuspi- 
dati,  or  the  canine ;  bicuspides,  or  the  small  grinders ;  and 
molares,  or  the  large  grinders. 

On  each  side  of  the  jaw,  supposing  it  divided  in  the  middle 
there  are  two  incisores,  one  cuspidatus,  two  bicuspides,  and  three 
molares.  They  occur  in  the  order  in  which  they  have  been 
named,  beginning  at  the  middle  of  the  jaw,  as  in  the  above 
figure. 

Each  tooth  is  divided  into  two  parts,  viz.  the  body,  or  that 
portion  which  is  bare,  and  projects  beyond  the  alveoli  and  gums ; 
and  the  root,  which  is  lodged  in  the  socket.  The  boundary 
between  these  parts,  which  is  embraced  by  the  gums,  is  called 
the  neck  of  the  tooth. 

The  body  and  roots  consist  of  a  peculiar  kind  of  bone  (dentine) 
which  is  more  firm  and  hard  than  the  substance  of  the  other 
bones ;  but  all  the  surface  of  the  body,  which  projects  beyond 


100  COMPOSITION  OF   THE  TEETH. 

the  gums,  is  covered  with  enamel,  a  substance  very  different  from 
common  bone. 

Every  tooth  in  its  natural  condition  has  a  cavity  in  it,  which 
commences  at  the  extremity  of  each  root,  and  extends  from  it  to 
the  body  of  the  tooth,  where  it  enlarges  considerably.  This  cavity 
is  lined  by  a  membrane,  and  contains  a  nerve,  with  an  artery 
and  vein,  which  originally  entered  the  tooth,  by  a  foramen  near 
the  point  of  the  root,  as  is  evidenf  during  the  growth  of  the  teeth. 
These  vessels,  and  the  nerve,  have  been  traced  into  the  teeth ; 
although  in  many  subjects  the  foramina  appear  to  be  closed  up. 
— A  third  substance  has  lately  been  discovered  by  Prof.  Ret- 
zius  of  Stockholm  as  entering  into  the..co'nGfyo£it]6n*of  the  teeth 
of  man,  called  the  cortical  substance  or  cementum.  It  com- 
mences at  the  lower  edge  of  the  enamel  and  surrounds  com- 
pletely the  fang.  In  many  of  the  lower  animals  it  is  found  also? 
on  the  faces  of  the  compound  teeth,  filling  up  the  spaces  between 
the  vertical  ridges  of  enamel. — 

Composition  of  the  Teeth. 

— The  bone  or  ivory  of  the  teeth,  now  called  Dentine,  (see 
Fig.  24,)  constitutes  the  whole  of  the  root,  and  a  greater  part 
of  the  body  and  neck.  The  cavity  in  the  centre,  for  the  lodg- 
ment of  the  pulp,  (cavitas  pulpi)  in  whichever  of  the  teeth  it 
is  examined,  presents  an  exact  similarity  of  shape  to  the  bodies 
and  fangs  of  the  teeth,  as  though  the  latter  had  been  moulded 
upon  the  pulp.  The  ivory  is  of  a  polished  pearly  whiteness, 
like  that  of  a  piece  of  white  satin.  It  is  composed  chemically 
both  of  animal  and  earthy  matter,  but  in  different  propor- 
tions from  ordinary  bone.  If  exposed  for  a  considerable 
Fig.  24.  time  to  the  action  of  a  weak  acid  solu- 

tion, the  earthy  matter  is  dissolved, 
and  there  is  left  a  flexible,  tenacious, 
dense,  and  homogeneous  mass,  much 
resembling  cartilage,  but  more  dense. 
If,  on  the  contrary,  it  is  exposed  to  the 
action  of  fire,  the  animal  matter  is  first 
blackened,  then  consumed,  and  there 
is  left  a  white,  hard,  friable  residue  of  calcareous  matter. 


COMPOSITION  OF  THE  TEETH.  101 

When  examined  with  the  microscope,  the  bone  or  ivory 
appears  to  consist  of  minute  branching  fibres,  which  begin  at  the 
pulp  and  run  toward  the  periphery  of  the  tooth,  and  aje  im- 
pacted in  some  homogenous  bony  tissue  lodged  between  them. 
— These  fibres  have  been  shown  by  Mr.  Nasmyth  to  be  nothing 
more  than  little  opaque  bodies,  the  nuclei  of  the  bone  or  ivory 
cells  arranged  in  a  linear  series. 

— The  enamel  or  vitreous  substance,  (see  Fig.  24,)  so  named 
from  its  resemblance  to  vitrified  minerals,  has  been  with 
greater  propriety  called  by  Blake,  the  cortex  striatum,  from  the 
lines  which  it  presents  upon  its  sides.  It  forms  a  covering 
nearly  a  line  in  thickness  upon  the  crown  of  the  teeth,  and  is 
thinned  down  at  its  termination  upon  the  neck.  It  is  composed 
of  minute  hexagonal  crystalline  fibres,  consisting  like  those  of 
the  ivory  of  minute  cells  filled  with  calcareous  substance  piled 
one  upon  another,  perpendicularly  to  the  bony  part,  and  so 
closely  compressed  together,  as  to  leave  no  obvious  interval 
between  them.  All  the  wear  of  the  teeth  takes  place,  therefore, 
at  the  end  of  these  fibres  and  not  upon  their  sides  ;  and  the 
enamel  is  rendered  by  this  arrangement  much  less  liable  to  frac- 
ture. 

— No  vessels  have  been  traced  to  this  substance,  nor  has  it 
ever  been  seen  like  the  bony  portion,  colored  by  madder  in 
young  animals  fed  on  this  substance  during  the  development 
of  the  teeth.  But  Mascagni,  infatuated  with  his  discoveries 
in  the  absorbent  system,  absurdly  regarded  this  substance  as 
entirely  formed  of  absorbent  vessels.*  It  is  exceedingly  hard 
and  strikes  fire,  on  collision  with  steel.  While  covering  the 
bone,  it  presents  a  milky  white  appearance ;  removed  from  it, 
it  is  semi-transparent  and  opaline. 

— The  enamel  is  thickest  on  those  parts  of  the  teeth  most 
exposed  to  friction,  as  on  the  horizontal  surfaces  of  the 
grinders,  the  edges  of  the  incisors,  and  the  points  of  the  cuspi- 
dati.  The  position  of  the  enamel  and  its  arrangement  into 
fibres  is  well  seen  in  Fig.  24. 


*  Vide  Prodrome. 
9* 


102         PURKINJE  AND  MULLER  ON  THE  TEETH. 

— The  enamel  and  ivory  of  the  teeth  are  the  most  indestructible 
after  death  of  all  parts  of  the  body.  In  opening  tumuli  or  other 
ancient  places  of  sepulchre,  they  are  frequently  found  to  have 
undergone  scarcely  any  decomposition. 

— The  cortical  substance  or  cementum,  see  Fig.  24,  consists  of  a 
thin  osseous  layer  developed  on  the  external  part  of  the  fangs, 
down  to  the  orifices  which  lead  to  the  cavity  of  the  tooth.  It  is 
essentially  of  the  same  structure  as  true  bone,  containing  the 
characteristic  corpuscles,  and  calcigerous  branching  tubuli  of 
that  tissue.  It  is  supposed  to  be  formed  by  ossification  of  the 
capsule  in  contact  with  the  fang,  and  is  certainly  the  seat  of  the 
exostosis  often  met  with  on  the  roots  of  the  teeth.  In  old  age  it 
makes  its  appearance  in  the  cavity  of  the  tooth,  and  is  formed 
from  the  membrane  of  the  pulp — the  pulp  shrinking  and  retiring 
in  proportion  as  the  cement  accumulates. 

— The  chemical  composition  of  the  two  substances  of  the  hu- 
man teeth,  consists,  according  to  Berzelius,  in  the  hundred 
parts,  of 

Enamel.  Bone. 

Animal  matter,  -       20.0 

Phosphate  of  lime,  with  fluate  of  lime,  88.5  -       64.3 

Carbonate  of  lime,  8.0  -         5.3 

Phosphate  of  magnesia,    -  1.5-1.0 
Soda,  with  some  chloride  of  soda,       -                               1.4 

Free  alkali  and  animal  matter,  2.0 

100.0  100.0 

— Purkinje  and  Miiller,  have  recently,  with  the  aid  of  the 
microscope,  investigated  very  minutely,  the  structure  of  the 
teeth,  and  their  discoveries  have  been  confirmed  by  many 
other  observers  of  high  reputation.  They  describe  the  bony 
part  of  the  tooth  as  consisting  of  fibres  running  parallel  to  each 
other  from  the  external  to  the  internal  surface  of  the  tooth, 
between  which  is  placed  a  semi-transparent,  homogeneous  por- 
tion. These  fibres  they  believed  to  be  really  tubular;  for  on 


PURKINJE  AND  MULLER  ON  THE  TEETH.         103 

bringing  ink  into  contact  with  them,  it  was  drawn  into  them, 
as  if  by  capillary  attraction.  These  tubes  Miiller  believed  to 
be  filled,  at  least  partially,  with  calcareous  matter,  which  was 
the  cause  of  the  whiteness  and  opacity  of  the  toofh.  In 
the  more  transparent  part  of  carious  teeth,  the  white  sub- 
stance in  these  tubes  presented  more  of  a  granular,  and  less  of 
a  compact  appearance,  under  the  microscope,  than  in  a  sound 
tooth. 

— The  white  color  and  opacity  of  these  tubes  were  removed 
by  the  application  of  acids.  On  breaking  a  thin  lamella  of  a 
tooth  transversely  in  regard  to  the  fibres,  and  examining  the 
edge  of  the  fracture,  he  perceived  the  tubes,  stiff,  straight,  and 
inflexible,  projecting  here  and  there  from  the  surfaces.  If  the 
lamella  had  previously  been  acted  on  by  acid,  the  tubes  were 
flexible,  transparent,  and  often  very  long.  Hence  Miiller 
inferred  that  the  walls  of  the  tubes  have  a  basis  of  animal  tissue, 
and  that  besides  containing  calcareous  matter  in  their  cavity, 
they  have  this  tissue  in  the  natural  state  impregnated  with 
calcareous  salts.  The  greater  part  of  the  earthy  matter  of  the 
tooth  is,  however,  contained  in  the  transparent  homogeneous 
portion  between  the  fibres,  in  which  it  can  be  rendered  visible 
in  a  granular  state  by  boiling  thin  lamina  of  teeth  in  a  ley  of 
potash. 

— Purkinje,  by  the  aid  of  high  magnifying  powers,  discovered 
the  corpuscles  that  characterize  true  bone,  in  layers  taken  from 
the  external  and  internal  surface  of  the  root ;  he  considers  the 
great  mass  of  the  tooth,  however,  as  destitute  of  organization. — 
— These  fibres  which  have  been  still  more  fully  proved  by 
Retzius*  to  be  true  canals,  having  their  own  walls,  are  differ- 
ently arranged  in  the  separate  substances  of  the  tooth,  but  are 
every  where  exceedingly  minute.  In  the  ivory  they  are  about 
g^th  of  a  line  in  diameter:  they  commence  by  open  orifices 
at  the  cavity  of  the  pulp,  and  extend  in  an  undulating  but 
nearly  parallel  direction  to  the  surface,  dividing  and  branching 


*  Mikroskopiska  Undersokningar  ofver  Tandernes  sardeles  Tandbenets, 
struktur :  Stockholm,  1837. 


104  OF  THE  ALVEOLI. 

in  their  course ;  the  branches  anastomosing  together,  and  com- 
municating occasionally  with  very  minute  calcigerous  cells, 
lodged  in  the  transparent  intertubular  structure,  which  may  be 
compared  to  the  corpuscles  of  ordinary  bone. 

The  fibres  or  filled  tubes  of  the  enamel  are  about  5£0th  of  a 
line  in  diameter,  and  are  hexagonal.  They  are  striated, 
arranged  parallel  to  each  other,  and  are  applied  by  their 
internal  extremities  to  corresponding  depressions  on  the  surface 
of  the  ivory. 

— The  ordinary  bony  tubuli  of  the  cement  or  cortical  substance 
communicate  here  and  there  with  the  branching  tubes  of  the 
ivory. 

— These  minute  but  interesting  details  in  regard  to  the  structure 
of  the  teeth,  which  are  found  to  vary  in  the  different  classes  of 
animals,  are  important,  not  only  as  furnishing  one  of  the  best 
methods  of  their  classification,  but  in  exhibiting  the  striking 
analogy  that  exists,  as  to  their  structure,  between  teeth  and 
bone.  The  tubes  or  canals  of  common  bone  are  occupied  by 
blood-vessels,  the  calcareous  matters  being  lodged  in  the  bony 
corpuscles  and  their  reticular  tubuli ;  while  those  of  the  teeth 
are  vascular  in  the  growing  state,  and  become  nearly  all 
filled  up  as  well  as  their  corpuscles  with  earthy  matter,  to 
give  that  great  degree  of  solidity  requisite  in  biting  and  masti- 
cation.— 

The  alveoli  or  sockets  of  the  teeth,  are  formed  upon  the  edge 
of  the  jaw :  the  bone,  of  which  they  consist,  is  less  firm  than 
any  other  part  of  the  jaws:  they  correspond  exactly  with  the 
roots  of  the  teeth  ;  and  are  lined  with  a  vascular  membrane, 
which  serves  as  a  periosteum  to  the  roots,  and  assists  in  fixing 
them  firmly. 

— They  are  developed  pari  passu,  with  the  teeth,  and  solely 
for  the  purpose  of  giving  them  a  lodgment ;  hence  when  the 
teeth  are  removed  from  the  jaw,  in  the  living  subject,  the 
sockets  subsequently  disappear  by  absorption,  as  being  of  no 
further  use.  There  are  two  sets  of  alveoli,  one  for  the  deci- 
duous teeth  of  the  child,  and  one  for  the  permanent  teeth  of 
the  adult.  Their  walls  are  formed  of  one  plate  on  the  external 


THE  ALVEOLI.  105 

side  of  the  jaw,  and  one  on  the  internal,  with  transverse  bony 
laminae  passing  between  them.  On  the  side  of  the  cavity 
which  they  form,  their  substance  is  loose  and  cellular  ;  on  their 
outer  side,  like  other  bones,  they  are  smooth  and  compact: 
— The  transverse  processes,  are  rather  more  prominent  than  the 
lateral  part  of  the  parietes,  corresponding  in  this  respect  inversely 
with  the  line  of  enamel  on  the  teeth. 

— The  enamel  terminates  on  the  neck  of  the  teeth  a  little  above 
the  level  of  the  sockets,  leaving  a  small  space  on  the  bony  part 
of  the  neck  round  which  the  gum  is  attached. 
— The  alveoli,  terminate  in  as  many  hollow  processes,  as  there 
are  fangs  to  the  teeth  which  they  lodge  :  and  at  the  bottom  of 
each  of  these  processes  there  are  one  or  more  minute  foramina, 
for  the  transmission  of  vessels  and  nerves  to  the  internal  mem- 
brane and  pulp  of  the  teeth. 

— The  mode  of  articulation  of  the  teeth  in  the  sockets  is  called 
gomphosis ;  even  in  their  perfect  state,  the  teeth  are  slightly 
movable  in  the  socket,  of  which  dental  surgeons,  occasionally 
take  advantage,  in  altering  the  direction  of  the  teeth,  by 
mechanical  means.  The  firmness  of  the  articulation,  depends 
upon  the  adaptation  in  size  and  shape  of  the  sockets  to  the 
fangs,  on  the  gum  which  surrounds  the  neck,  of  the  periosteum 
of  the  sockets  which  is  continuous  with  that  of  the  fangs,  and 
of  the  vessels  and  nerves  which  enter  into  the  foramina  of  the 
fangs. 

The  teeth  of  different  kinds  differ  greatly  from  each  other,  in 
form  and  size. 

The  body  of  the  incisores  is  broad,  with  two  flat  surfaces, 
one  anterior  and  the  other  posterior  ;  the  anterior  surface  is 
rather  convex  and  the  posterior  concave  ;  they  meet  in  a  sharp 
cutting  edge.  At  this  edge  the  tooth  is  thinnest  and  broadest; 
it  gradually  becomes  thicker  and  narrower,  as  it  is  nearer  the 
neck.  The  enamel  continues  farther  down  on  the  anterior  and 
posterior  surfaces  than  on  the  sides. 

The  incisores  of  the  upper  jaw  are  broader  than  those  of  the 
lower ;  especially  the  two  internal  incisores. 

The  cuspidati  are  longer  than  any  other  teeth,  and  are  thicker 


106  PERMANENT  TEETH. 

than  the  incisors.  Their  edges  are  not  broad,  as  those  of  the 
incisors,  but  pointed  ;  this  point  is  much  worn  away  in  the  pro- 
gress of  life. 

The  enamel  covers  more  of  the  lateral  part  of  these  teeth 
than  of  the  incisors. 

The  bicuspides  are  next  to  the  cuspidati,  two  on  each  side. 
They  resemble  each  other  strongly  ;  but  the  first  is  smaller  than 
the  other,  although  it  generally* has  a  longer  root.  The  bodies 
are  flattened  laterally,  but  incline  to  a  roundish  form.  On  the 
middle  of  the  grinding  surface  are  depressions  which  make  the 
edges  prominent.  On  the  external  edge  there  is  generally  one 
distinct  point  in  each  of  the  bicuspides.  The  internal  edge  is 
lower  than  the  external  in  the  first  bicuspis,  which  gives  it  a 
resemblance  to  the  cuspidatus.  In  the  second  bicuspis,  the 
internal  edge  is  more  elevated,  although  the  point  is  not  so 
distinct  as  it  is  on  the  external  edge. 

The  bicuspides  have  generally  but  one  root,  which  is  often 
indented  lengthwise,  so  as  to  resemble  two  roots  united. 

The  three  molares  or  large  grinders  are  placed  behind  the 
bicuspides,  on  each  side.  The  first  and  second  strongly  resem- 
ble each  other,  but  the  third  has  several  peculiarities.  The 
body  of  the  large  grinders  is  rather  square  ;  the  grinding  surface 
has  often  five  points,  and  three  of  these  are  on  the  external  side. 
In  the  upper  jaw  these  teeth  have  three  roots,  two  situated 
externally,  and  one  internally,  which  is  very  oblique  in  its 
direction  ;  they  are  all  conical  in  their  form.  It  seems  probable 
that  the  roots  of  these  teeth  are  arranged  in  this  way  to  avoid 
the  antrum  maxillare.  The  molares  of  the  lower  jaw  have  but 
two  roots,  which  are  flat,  and  are  placed  one  anterior  and  the 
other  posterior ;  in  each  of  these  broad  roots  there  are  two 
canals,  leading  to  the  central  cavity  ;  whereas,  in  each  root  of 
the  upper  molares  there  is  but  one.  The  third  grinder  is  called 
dens  sapientia^  from  its  late  appearance.  It  is  shorter  and 
smaller  than  the  others  ;  its  body  is  rather  rounder,  and  its  roots 
are  not  so  regular  and  distinct  ;  for  they  are  sometimes  com- 
pressed together,  and  sometimes  there  appears  to  have  been 
but  one  root  originally,  when  the  whole  tooth  has  a  conical 


DECIDUOUS  TEETH.  -        107 

appearance.  In  some  cases  the  denies  sapientiae  take  an 
irregular  direction,  and  shoot  against  the  adjoining  teeth. 

Infants  have  a  set  of  deciduous  teeth,  which  differ  in  several 
respects  from  those  of  adults.  They  are  but  twenty  in  ntfmber ; 
the  five  on  each  side  of  each  jaw,  consist  of  two  incisores,  one 
cuspidatus,  and  two  molares  or  large  grinders.  The  first  of  them 
generally  protrudes  through  the  gums  between  the  fourth  and 
eighth  months  of  age  ;  the  last  about  the  end  of  the  second  year. 
They  commonly  appear  in  pairs,*  which  succeed  each  other  at 
irregular  intervals.  Those  of  the  lower  jaw  are,  in  most  cases, 
the  first.  The  order  of  their  appearance  is  this  :  the  central 
incisors  appear  first,  then  the  external  incisors  on  each  side  ; 
after  these  the  first  molaris,  then  the  cuspidatus,  and  finally 
the  last  molaris  on  each  side.  There  are  many  deviations 
from  this  order  of  succession,  but  it  takes  place  in  a  majority  of 
cases. 

These  deciduous  teeth  become  loose,  and  are  succeeded  by 
those  which  are  more  permanent,  nearly  in  the  same  order  in 
which  they  appeared,  but  with  a  progress  much  more  slow. 
The  incisores  generally  become  loose  between  the  sixth  and 
seventh  year  ;  the  first  molares  about  the  ninth,  the  cuspidati 
and  the  second  molares  not  until  the  tenth  or  twelfth,  or  even 
fourteenth  year.  The  bicuspides  take  the  places  of  the  infant 
molares. 

The  three  permanent  molares  appear  in  the  following  order : 
the  first  of  them  protrudes  a  short  time  before  the  front  teeth  are 
shed ;  it  is  the  first  of  the  permanent  teeth  which  appears, 
and  is  seen  between  the  sixth  and  seventh  year.  The  second 
molaris  appears  soon  after  the  cuspidati  and  the  second  bicus- 
pides are  seen.  There  is  then  a  long  interval  ;  for  the  last 
molaris  or  dens  sapientise  is  seldom  seen  before  the  twentieth 
year,  and  sometimes  not  until  the  twenty-fifth. 

The  teeth  are  formed  upon  pulpy  substances,  which  are 
situated  in  the  alveoli,  and  are  contained  in  capsules.  A  shell 
of  bone  is  first  formed  upon  the  surface  of  the  pulp,  which 

*  The  two  teeth  of  a  pair  do  not  appear  at  the  same  precise  time,  but  very 
near  to  each  other. 


108  DEVELOPMENT  OF  THE  TEETH. 

gradually  increases,  and  the  pulp  diminishes  within  it.  The 
body  of  the  tooth  is  produced  first,  and  the  root  is  formed 
gradually  afterwards ;  during  its  formation  the  root  has  a  large 
opening  at  the  extremity,  which  is  gradually  diminished  to  the 
small  orifice  before  described.  The  roots,  as  well  as  the  body, 
are  formed  upon  the  pulpy  substance,  which  gradually 
diminishes,  as  they  increase.  After  the  external  surface  of  the 
body  of  the  tooth  is  formed*  the  enamel  begins  to  appear 
upon  it,  and  gradually  increases,  until  it  is  completely  invested. 
It  is  probable  that  the  enamel  is  deposited  upon  the  body  of 
the  tooth  by  the  membranous  capsule  which  contains  it.  This 
substance,  which  appears  to  be  formed  of  radiated  fibres,  is 
harder  and  less  destructible  than  bone.  Like  the  substance 
of  bone,  it  is  composed  of  phosphate,  with  a  small  propor- 
tion of  the  carbonate  of  lime;  but  it  is  destitute  of  the  cartila- 
ginous or  membraneous  structure  which  is  demonstrable  in 
bone. 

The  pulpy  substances,  or  rudiments  of  teeth,  may  be  seen  in 
the  foetus,  when  about  four  months  old.  At  six  months, 
ossification  can  be  seen  to  have  commenced  on  the  pulps  of 
the  incisores.  At  the  time  of  birth,  the  bodies  of  the  infant 
teeth  are  distinctly  formed.  The  alveoli,  at  first,  have  the 
appearance  of  grooves  in  the  jaw,  which  afterwards  are  divided 
by  transverse  partitions ;  they  enlarge,  in  conformity  to  the 
growth  of  the  teeth,  and  appear  to  be  altogether  influenced  by 
them. 

The  permanent  teeth  are  formed  very  early  :  the  rudiments 
of  the  first  permanent  grinder  on  each  side  have  commenced 
their  ossification  at  birth.  At  the  same  time,  the  rudiments  of 
the  permanent  incisors  are  to  be  perceived  ;  and  their  bodies 
will  be  found  nearly  ossified,  by  the  time  the  infant  incisors 
are  protruded  completely  through  the  gums.  About  the  age  of 
six  years,  if  none  of  the  infant  teeth  are  shed,  there  will  be 
forty-eight  teeth  in  the  two  jaws,  viz :  the  twenty  infantile, 
and  twenty-eight  permanent  teeth,  more  or  less  completely 
formed. 

— From  their  mode  of  development,  apparent  structure,  and 


.c      *&f* 


DEVELOPMENT  OF  THE  TEETH.  109 

connexions  with  the  rest  of  the  economy,  the  teeth  were  prior  to 
the  microscopical  researches  above  detailed  considered  analogous 
to  the  hair,  nails,  and  feathers  of  mammiferae  and  birds,  and  to 
the  shells  of  molluscae.  It  cannot  be  said  that  the  teeih  are 
absolutely  inorganized,  that  they  are  mere  concretions  of  an 
effused  fluid,  since  there  is  no  part  appertaining  to  living  beings, 
entirely  destitute  of  life ;  but  in  the  hard  structure  of  the  teeth, 
no  anatomist  has  yet  demonstrated  either  vessels  or  nerves,  though 
there  are  practical  dentists,  who  assert  that  they  have  seen  blood 
issu«  from  the  bony  part  of  the  teeth,  in  some  of  their  operations.* 

*  Hunter  denies  positively  the  existence  of  any  vessels  passing  between  the. 
pulp  and  bone  of  the  teeth,  as  he  was  not  able  to  render  them  manifest  by  injec- 
tion, as  the  coloring  matter  does  not  pass  into  them  when  animals  are  fed  upon 
madder,  except  in  the  forming  state,  and  as  they  do  not  share  in  the  general  soft- 
ening of  the  bones,  in  rickets  and  malacosteum.  Blake  believed  that  these 
vessels  did  exist,  but  were  difficult  to  demonstrate,  like  those  that  we  know  to 
pass  in  the  eye  from  the  capsule  of  the  crystalline  lens,  to  the  lens  itself;  Beclard, 
that  there  were  no  vessels  in  the  bone  of  the  teeth,  continuous  with  those  of  the 
pulp,  but  that  the  former  received  continually  from  the  latter  a  nourishing  liquid 
which  penetrated  it  by  imbibition,  and  that  it  was  situated  in  regard  to  the  pulp, 
as  the  hair  and  nails  to  the  vascular  part  of  the  skin.  But  the  morbid  altera- 
tions which  take  place  in  the  body  of  the  teeth,  the  softening  and  exostosis  seen 
frequently  at  their  roots,  and  the  fusion  of  the  latter  occasionally  to  the  bottom 
of  the  alveoli,  render  their  vascularity  highly  probable. 

The  fang  of  a  perfectly  developed  tooth,  is  covered  closely  by  a  membrane, 
called  its  periosteum,  which  is  continuous  with  the  periosteum  of  the  socket,  and 
is  on  all  hands  admitted  to  be  vascular  ;  the  internal  cavity  is  also  lined  by  a 
highly  nervous  and  vascular  membrane.  Both  of  these  are  intimately  con- 
nected with  the  bony  structure  of  the  tooth,  and  require  a  little  force  to  separate 
them.  This  connection  Mr.  T.  Bell  believes  to  be  made  by  vessels  and  probably 
nerves,  which  pass  between  them  and  the  bone.  Though  no  artificial  injection? 
has  been  made  of  the  teeth,  this  writer  has  seen  them  tinged  with  a  bright  yel- 
low in  a  young  woman  who  died  of  jaundice ;  and  where  death  has  taken  place 
from  hanging  or  drowning,  when  there  is  usually  a  congestion  of  the  capillary 
system,  "  he  has  found  the  osseous  part  colored  with  a  dull  deep  red  which  could 
not  possibly  take  place  if  they  were  devoid  of  a  vascular  system ;  in  both 
instances  the  enamel  remained  wholly  free  from  discoloration."  I  have  observed 
the  same  thing  in  the  teeth  of  subjects  who  have  died  of  cholera.  The  existence 
of  nerves  in  the  bony  part  of  the  teeth  Bell  considers  manifested  by  the  facts 
common'y  observed  by  dentists  ;  in  filing  the  teeth  no  pain  whatever  is  produced 
till  the.  enamel  is  removed ;  but  the  instant  the  file  begins  to  act  upon  the  bone, 
the  sensation  is  exceedingly  acute  :  and  when  the  gums,  alveoli  and  periosteal 
lining  membrane,  have  receded  from  the  teeth  so  as  to  leave  the  bony  part  bare, 
it  is  exquisitely  sensitive  when  touched  with  any  hard  instrument. 

He  admits  likewise  the  existence  of  absorbents  in  the  bony  part  of  the  teeth, 
for  in  a  tooth  in  which  inflammation  had  existed  for  a  considerable  time,  he 
10 


110  DEVELOPMENT  OF  THE  TEETH. 

— If  the  pulp  which  produces  them  be  destroyed  from  any 
cause,  they  lose  the  little  vitality  that  they  may  possess,  become 
foreign  bodies  mechanically  retained  in  the  living  parts,  and 
sooner  or  later  are  thrown  off. 

— The  teeth  are  distinguished  from  the  common  bony  tissue,  by 
the  absence  of  any  demonstrable  cellular  or  vascular  parenchyma 
in  their  composition,  by  their  being  in  part  exposed  to  the 
contact  of  the  atmosphere,  whiah  no  bone  can  be  without  losing 
its  vitality,  by  the  enamel  which  covers  them  externally,  by 
their  successive  evolution  and  renovation  at  certain  periods  of 
life,  and  lastly  by  their  wearing  out,  and  being  lost  in  old  age, 
whilst  the  vital  actions  are  still  going  on  in  the  rest  of  the  economy. 
— In  many  of  the  lower  animals  the  teeth  are  evidently  a 
production  of  the  skin  or  dermoid  tissue,  which  is  reflected  in 
at  the  commencement  of  the  digestive  passages,  and  many 
modern  anatomists  have  for  the  reasons  above  mentioned,  con- 
nected them  with  the  description  of  the  digestive  organs.  They 
have,  however,  again  been  restored  for  purposes  of  convenience 
to  the  student,  to  their  proper  connexion  with  the  bones  in  which 
they  are  developed. 

Development  of  the  Teeth. 

— The  teeth,  as  we  have  before  observed,  are  developed  on  a 
principle  different  from  that  of  other  parts  of  the  body,  by 
germs  or  gemmules.  If  the  jaws  of  a  foetus  are  examined  with 
care,  even  at  the  period  of  two  months*  after  conception,  an 
extremely  soft,  jelly-like  substance  is  seen  lying  in  a  groove 
along  the  edge  of  each  maxillary  arch.  At  the  third  month  it  is 
more  consistent,  and  two  plates  of  bone  have  sprung  up  at  its 
sides,  which  are  the  rudiments  of  the  external  and  internal  alveo- 
lar plates.  Shortly  after  this  period,  the  pulpy  substance  sepa- 
rates into  distinct  portions,  and  rudiments  of  the  transverse  plates 
of  the  alveoli  are  seen  shooting  across,  from  side  to  side.  These 
distinct  portions  of  the  pulpy  substance,  have  a  papillary  form 
and  are  the  germs  or  rudiments  from  which  the  teeth  are  devel- 

found  after  its  extraction  an  abscess  in  the  very  centre  of  the  bony  structure, 
communicating  with  the  natural  cavity  and  filled  with  pus. — p. 
*  T.  Bell.— Beclard. 


DEVELOPMENT    OF   THE    TEETH.  Ill 

oped ;  each  is  partially  enclosed  in  a  sac,  and  receives  branches 
from  the  vessels  and  nerves  which  run  along  the  bottom  of  the 
groove.  At  the  fourth  month,  the  enveloping  sac  is  thick  in  its 
texture,  and  consists  of  two  layers,  which  are  easily  separated 
after  a  short  maceration.  Both  of  these  layers,  Fox  and  T.  Bell 
have  proved,  by  their  injections,  to  be  vascular:*  laying  loosely 
within  this  double  sac  is  the  gelatinous  vascular  pulp  itself, 
covered  by  an  extremely  thin,  delicate  vascular  membrane,  (to 
which  it  is  closely  united  by  vessels,)  which  secretes  the  bony 
part  of  the  tooth,  and  is  a  sort  of  internal  periosteum.f  The 
pulp  and  its  membrane  receive  their  vascular  and  nervous  fila- 
ments from  the  proper  dental  vessels  and  nerves,  which  run 
along  the  groove  in  the  jaw.  The  double  saccular  membrane 
receives  its  vessels  and  nerves  solely  from  the  gums  ;  and  the 
only  attachment  between  this  and  the  membrane  of  the  pulp,  is 
near  the  base  of  the  latter,  where  the  dental  vessels  enter  it. 
The  sac  is  closely  united  to  the  gum,  hence  if  we  tear  away  the 
gum  that  covers  the  jaws,  we  necessarily  bring  with  it  the  entire 
structure  of  the  germ. 

— If  at  this  period,  the  fourth  month,  we  open  the  germ,  w,e 
find  the  pulp  presenting  exactly  the  size  and  shape  of  the  body 
of  the  teeth  first  cut,  (incisors)  and  that  its  membrane  has 
already  commenced  the  deposit  of  the  bony  tip. 
— At  birth,  ossification  will  be  found  to  have  commenced  on  all 
the  pulps  of  the  temporary  teeth,  (the  body  of  the  incisors 
being  nearly  completed,)  and  on  each  of  those  of  the  anterior 
permanent  grinders.  The  commencement  of  ossification  is  by 
three  points  in  the  incisors,  which  form  their  serrated  edges 
as  seen  on  their  first  development,  by  a  single  point  for  the 
canine,  two  for  the  bicuspide,  and  three,  four,  or  five  on  the 

*  Hunter  declared,  that  the  external  is  soft  and  spongy,  without  any  vessels; 
the  other  much  firmer,  "  and  extremely  vascular."  Blake  on  the  contrary 
asserts,  that  the  external  is  spongy  and  full  of  vessels,  the  internal  one  is  more 
tender  and  delicate,  and  seems  to  contain  no  vessels  capable  of  containing  red 
blood. 

f  This  membrane  is  called  by  Bell  the  proper  membrane  of  the  pulp,  and  was 
conjectured  by  Blake,  with  much  probability,  to  be  a  "propagation  of  the  peri- 
osteum of  the  jaw."  Blake  on  the  Teeth,  p.  8. — 


112  THE    ENAMEL. 

large  molar,  according  to  the  number  of  processes  which  they 
present.  Continuous  deposition  of  the  bony  matter  from  the 
membrane  of  the  pulp,  unites  these  points  together,  and  by 
degrees  at  different  epochs,  all  the  bodies  are  formed  ;  the  pulp 
retiring  as  it  were,  as  the  deposition  of  bone  goes  on  and 
encroaches  upon  its  cavity,  and  elongates  itself  downward, 
into  the  shape  of  the  fang.  This  is  finally  formed  in  the  same 
manner  as  the  bodies,  and  the»  pulp  is  completely  enclosed  in 
the  bony  case  of  the  tooth,  except  at  the  foramina  where  the 
vessels  and  nerves  enter.  Where  more  than  one  fang  exists  to 
a  tooth,  the  lower  part  of  the  pulp,  is  previously  divided  into 
an  equal  number  of  processes,  by  little  bony  partitions  which 
shoot  across  from  the  sides  of  the  alveoli. 

Of  the  Enamel. 

— When  the  development  of  the  bony  shell  has  fairly  begun,  the 
inner  layer  of  the  sac  becomes  thickened  and  more  vascular, 
receives  a  greater  amount  of  blood,  becomes  closely  attached  to 
the  neck,  and  forms  a  loose  capsule  over  the  body.  From  the 
internal  face  of  this  membrane,*  is  poured  out  a  thickened 
whitish  granular  fluid,  called  by  Mr.  Goodin  the  enamel  organ 
which  Berzelius  considers  of  the  nature  of  lactic  acid  ;  this  is 
speedily  consolidated  into  a  dark  chalky  substance,  deposited 
first  upon  the  tips  of  bone,  and  gradually  extending  down  in 
layers  till  it  covers  the  whole  crown  of  the  teeth.  This  is  the 
enamel.  It  becomes  gradually  whiter  and  harder,  as  though 
by  a  more  perfect  crystallization,  but  ^near  (o  the  period  at 
which  the  teeth  are  cut,)  it  is  still  so  soft,  as  to  be  frequently  cut 
with  the  gum  lancet. 

*  Blake  believed  that  in  man,  the  enamel  was  formed  solely  by  the  inner 
membrane  of  the  sac.  The  external  contributing  nothing  to  the  structure  of 
the  teeth.  But  in  graminivorous  animals,  where  the  flinty  covering  of  the  food 
they  feed  on  requires  a  more  perfect  grinding  apparatus,  he  thought  the  external 
membrane  performed  an  important  part,  in  adding  another  element  to  the  struc- 
ture of  the  molar  teeth,  called  by  him,  crusta  petrosa.  The  cutting  teeth  are 
constructed  as  those  of  man.  In  these  animals  the  enamel  of  the  grinders  does 
not  form  a  continuous  smooth  layer  as  in  man,  but  passes  a  little  way  into  the 
body  of  the  teeth,  and  is  arranged  in  the  form  of  vertical  layers,  between  which 


THE    PERMANENT  TEETH.  1 13 

— Of  the  three  membranes  of  the  germ  or  follicle,  one  only 
may  be  considered  as  permanent,  that  of  the  pulp  or  internal, 
which  secretes  the  bone  of  the  tooth. 

— The  two  outer,  or  those  of  the  sac,  cover  the  crown -of  the 
tooth  ;  and  as  this  is  pushed  forwards  by  successive  depositions 
of  bony  matter  from  within,  they  are  pressed  upon  and  wasted 
away  by  absorption,  like  the  gum,  in  direct  proportion  with 
the  advancement  of  the  tooth,  so  that  in  perfectly  natural  den- 
tition, there  is  little  tension  or  pressure  felt.  This  is  called 
cutting  the  teeth,  a  name  which  expresses  the  fact,  sufficiently 
well,  but  literally  conveys  a  wrong  idea. 

— In  cases  of  difficult  dentition,  the  membranes  of  the  sac  re- 
tain their  density  and  vascularity,  and  are  probably  thickened 
by  inflammation,  and  the  bony  layers  formed  from  the  pulp, 
resisted  in  their  advancement  by  these  membranes,  make 
compression  upon  the  pulp  and  dental  nerves ;  this,  like 
continued  pressure  made  in  other  parts  of  the  body,  becomes 
exquisitely  painful,  and  gives  rise  to  distressing  sympathetic 
disturbances.  The  relief  procured  by  cutting  the  gums  and 
sac,  will  be  more  or  less  immediate,  according  to  the  degree 
of  compression  and  inflammation  of  the  pulp. 
— The  periosteum  covering  the  fangs  of  the  tooth,  is  a  reflected 
continuation  of  the  periosteum  lining  the  socket,  and  this  again 
is  continuous  with  that  lining  the  jaw. 

Of  the  Permanent  Teeth. 

— The  adult  or  permanent  teeth,  are  developed  in  a  manner 
almost  exactly  analogous  to  the  deciduous  or  infantile.  The 
germs  of  many  of  them  are  distinctly  perceptible  in  the  gums 
of  the  infant  at  birth.  They  are  placed  at  first  deep  in  the  jaw 

after  the  inner  membrane  of  the  sac  has  been  removed  by  absorption,  the  outer 
one,  according  to  Bell,  deposits  the  pars  petrosa,  and  fills  up  the  intervening 
space.  This  is  a  substance  harder  than  the  bone,  but  softer  than  the  enamel ; 
and  the  advantage  derived  from  it  is,  that  it  is  worn  oft'  by  trituration  more 
readily  than  the  enamel,  so  that  the  latter  is  constantly  maintained  in  sharp 
prominent  lines  upon  the  surface  of  the  teeth.  The  same  object  is  here  insen- 
sibly attained,  as  a  natural  consequence  of  the  difference  in  density  of  these 
parts,  which  the  miller  effects  with  much  labor  with  his  pick-hammer,  on  the 
burr-stones  of  his  mill. — P. 
10* 


114  THE  PERMANENT  TEETff. 

at  the  inner  side  of  those  of  the  deciduous  teeth,  to  the  sac  of 
which  they  are  attached  at  top  by  a  neck-like  process,  as  seen 
in  Fig.  25.  As  the  infantile  teeth  rise  up  and  make  their  way 

Fig.  25. 


through    the  gum,   this    process    becomes  connected  with    the 
gum,  and   forms  what  is  called   by   Hunter  the  gubernaculum^. 
dentis,  from   its   influence  in  giving  the   permanent  teeth  their 
proper    vertical    direction,   and    preventing   their   making    their 
way  at  random  through   the   sides,  as  they  do   occasionally  in 
cases  where  the  gubernaculum  has  been  destroyed. 
— Delabarre    has    given    the    gubernaculum    the   name  of  iter 
dentis,  from  an  erroneous  belief  that   it  was  tubular,  like  the 
duct  of  a  sebaceous  follicle,  and  gradually  opened  as  the  tooth 
progressed. 

— At  the  fifth  month  of  foetal  life,  according  to  Bell,  and  the 
eighth  and  ninth,  according  to  Blake  and  Fox,  the  germs  of  the 
first  permanent  molars,  may  be  seen  at  the  outside  of  the  in- 
fantile row,  and  those  of  the  permanent  incisors  behind  the 
deciduous.  Fig.  25 — 1,  2,  shows  the  attachment  of  the  incisor 
and  molar  germs  of  the  two  sets,  just  prior  to  the  eruption  of 
the  first.  The  permanent  germ  is  at  first  placed  in  the  socket 
of  the  deciduous  tooth,  of  which  it  appears,  on  first  view,  to 
be  an  offshot  or  gemmiperous  production.  Its  vessels  and 
nerves  are  believed  to  be  mere  branches  of  those  of  the  deci- 
duous set.  By  degrees  a  distinct  socket  is  formed  for  it  be- 
hind the  latter,  and  its  process  or  gubernaculum  is  elongated, 
as  seen  in  Fig.  25 — 3.  When  the  deciduous  teeth  have  cut  the 
gum,  the  two  sockets  are  completely  distinct,  as  seen  in  Fig. 
26,  and  the  gubernaculum  is  attached  to  the  gum. 
— Ossification  first  commences  in  the  permanent  set  on  the 
anterior  molares,  and  may  be  seen  at  birth  ;  at  the  age  of 


DEVELOPMENT  OF  THE  TEETH.  115 

Fig.  26.  twelve    months,    it   has    progressed    to  a 

considerable  extent  upon  these  as  well  as 
upon  the  incisors  and  the  lower  cuspi- 
data.  At  the  sixth  or  seventh  year  of 
age  the  whole  of  the  permanent  teeth  are 
more  or  less  ossified,  and  the  incisors  are 
so  far  completed  as  to  be  nearly  ready  to 
make  their  appearance  through  the  gum. 
At  this  period  there  are  no  less  than 
forty-eight  teeth  in  the  two  jaws,  the  twenty  deciduous  and 
the  twenty-eight  permanent,  which  are  in  different  degrees  of 
development.  The  last  molars  do  not  begin  to  ossify  till  the 
ninth  year,  and  are  the  last  of  all  to  make  their  appearance 
through  the  gum,  whence  they  have  received  the  name  of  denies 
sapientm  or  wisdom  teeth. 

— The  permanent  teeth,  which  are  more  in  number  and 
individually  of  larger  size  and  form  a  larger  arch  than  the 
temporary,  are  developed  at  successive  intervals,  so  as  to 
correspond  exactly,  with  the  increasing  size  of  the  jaws  from 
the  infantile  to  the  adult  state.  Hence  they  cannot  correspond 
in  position  with  the  deciduous  teeth ;  the  outer  permanent 
incisor  will  rise  up  near  the  cuspidatus,  and  the  permanent 
cuspidatus  near  the  first  molar  of  the  deciduous  set. 
— Exactly  in  proportion  as  the  bodies  of  the  permanent  teeth 
are  completed  and  approach  the  gum,  the  roots  of  the  decidu- 
ous are  removed  by  absorption,  till  finally  the  bodies  of  the 
latter  only  are  left  fixed  mechanically  in  the  gum,  and  are 
tumbled  off  at  the  slightest  effort.  The  process  of  the  removal 
of  the  fangs  is  not  perfectly  understood  ;  it  is  not  as  was  once 
supposed  produced  by  the  pressure  of  the  subjacent  tooth,  for 
very  frequently  the  commencement  of  absorption  is  at  the 
neck,  and  not  at  the  root  of  the  tooth,  where  no  pressure  can 
come,  and  occasionally  takes  place  even  where  the  germ  of  the 
permanent  tooth  has  been  destroyed.  It  is  more  probably 
owing  to  the  enlarged  vessels  of  the  growing  permanent  teeth, 
which  come  from  the  same  branch  with  those  of  the  deciduous, 
carrying  off  all  its  blood  by  derivation,  which  leads  to  the 


116  DEVELOPMENT  OF  THE  TEETH. 

wasting  of  the  latter  set,  a  process  of  which  we  find  the  analogue 
in  the  development  of  many  parts  of  the  foetus. 
— Below  is  a  tabular  view  of  the  appearance  of  the  temporary- 
teeth,  and  also  of  the  periods  at  which  they  are  changed  for  the 
permanent. 

— It  is  to  be  taken,  however,  as  a  general  rule  liable  to 
continual  exceptions,  not  only  in  regard  to  the  time,  but  also 
as  to  the  regular  order  of  appearance.  As  a  general  rule,  the 
teeth  of  the  lower  jaw  appear  first,  then  the  corresponding 
teeth  of  the  upper. 

Deciduous  Teeth. 

From  5  to  8  months,  the  four  central  incisors, 

"        7  "  10       "  four  lateral  incisors, 

"      12  "  16       "  four  anterior  rnolares, 

"14  "  20       "  four  cuspidati, 

"      18  "  36       "  four  posterior  molares. 

Permanent  Teeth. 

— The  first  permanent  molares  usually  pierce  the  gum  before 
the  fall  of  the  central  incisors,  and  their  appearance  indicates  the 
approaching  change. 

— The  following  are  about  the  medium  periods  at  which  they 
are  cut,  but  there  is  a  great  degree  of  variation  in  this  respect. 
Those  of  the  lower  are  here  indicated,  and  they  most  commonly 
precede  the  upper  by  about  two  or  three  months. 

About        6|  years,  the  anterior  molares, 

"  7  "  central  incisors, 

"  8  "  lateral  incisors, 

"  9  "  anterior  bicuspides, 

"  10  "  posterior  bicuspides, 

11  to    12  "  cuspidati, 

12  "     13  "  second  molares, 

17    "     19       "  third   molares  or  denies  sapientice. 

— Fig.  8  *is  a  side  view  of  a  beautiful  s  of  the  permanent 
teeth  of  both  jaws,  fitted  in  their  socke'  showing  the  exact 
manner  in  which  the  surfaces  of  ea^i  set  are  adjusted  to  each 


ABERRATIONS    OP    DENTITION.  117 

other,  and  the  smaller  dimensions  of  the  fangs  of  the  wisdom 
teeth,  owing  to  the  contracted  space  in  which  they  are 
developed.  These  teeth  decay  early,  are  comparatively  of 
little  utility,  and  probably  from  the  same  cause ;  for  in  cases, 
where  prior  to  their  development  one  of  the  molares  in  front 
of  them  have  been  removed,  they  take  a  more  forward 
position,  are  developed  with  larger  fangs,  and  become  much 
more  serviceable. 

— When  the  first  teeth  have  made  their  appearance  through 
the  gum,  they  are  not  yet  completed  ;  the  process  of  thickening 
the  body  by~  layers  from  within,  and  of  lengthening  the  root 
below,  is  for  a  time  still  continued  by  the  pulp.  After  their 
completion,  the  only  physiological  changes  they  undergo,  is 
the  wearing  down  of  the  bodies  by  friction,  and  the  filling  up 
of  the  top  of  their  cavity  within  by  the  pulp,  with  a  yellowish 
bony  matter  in  old  age,  (cementum,)  which  prevents  the 
exposure  of  the  cavity,  and  protects  the  vasculo-nervous  pulp, 
which  is  so  exquisitely  sensitive,  as  to  be  considered  by  some 
in  the  light  of  a  nervous  ganglion.  This  latter  process  unhap- 
pily is  not  universal,  and  is  especially  defective  when  the  teeth 
decay  early  in  life,  apparently  before  the  period  nature  has 
assigned  them. 

* 

Aberrations  of  Dentition. 

— Occasionally  at  birth  teeth  have  been  found  developed  on 
the  surface  of  the  gum,  as  in  the  cases  of  Louis  XIV.  of  France 
and  Richard  III.  of  England  :  in  such  cases  they  are  generally 
mere  shells,  and  are  quickly  shed,  and  below  exist  the  double 
series  of  germs,  which  are  developed  in  the  regular  order. 
— In  some  rare  cases,  from  the  non-existence  or  disease  of  the 
germs,  no  teeth  have  ever  been  developed.*  Borelli  mentions 
a  case  of  this  sort  occurring  in  a  woman  then  seventy-two 
years  old. 

— Sometimes  the  temporary  teeth  only  exist,  which  fall  at  the 
regular  period  and  ?s  never  replaced.  Occasionally  the  set 

*  Oudet.  Consid.  sur  la  Nature  des  Dents  et  leur  Alterations  ;  Journal  Univ. 
Des  Sciences  Med.  torn.  43,  1826. 


113  OS    HYOIDES. 

of  permanent  teeth  have  consisted  of  double  or  molar  teeth  all 
round.  Sometimes  the  appearance  of  the  temporary  teeth  has 
been  protracted  to  the  sixth  or  seventh  year,  and  even  then 
followed  at  regular  intervals  by  the  permanent  set.  The 
number  of  the  permanent  teeth  are  sometimes  less  than  usual, 
in  consequence  of  the  non-development  of  the  wisdom  teeth, 
which  remain  locked  up  in  the  jaw,  and  occasionally  produce 
pain,  and  even  abscesses  in  the1  bony  structure. 
— Sometimes  there  are  supernumerary  teeth.  Haller  has  seen 
in  an  infant  of  fourteen  years^seventy-two  teeth,  thirty-six  in 
each  jaw,  which  appeared  to  depend  upon  a  greater  number 
than  usual  of  the  dental  germs.  Some,  fond  of  the  marvelous, 
have  described  the  eruption  of  a  third  set  of  teeth  analogous  to 
the  two  first:  but  according  to  Hudson  and  others,  this 
appearance  has  probably  been  owing  to  the  tardy  removal  of 
the  deciduous  set,  and  the  late  supplial  of  their  place  by  the 
permanent  teeth. 

"—Sometimes  the  direction  of  the  teeth  is  vicious,  leading  into 
the  ramus  of  the  jaw,  or  upon  the  outer  or  inner  surface  of  the 
gums ;  or  upon  the  roof  of  the  mouth.  Accidental  develop- 
ments of  teeth  have  likewise  been  met  with  in  the  orbit,  the 
tongue,  pharynx,  stomach,  and  not  unfrequently  in  the  ovaries 
and  uterus. — 

Os  Hyoides. 

The  05  hyoides  is  a  small  insulated  bone,  supported  between 
the  lower  jaw  and  the  larynx,  by  muscles  and  ligaments, 
which  proceed  from  the  neighboring  parts  in  various 
directions. 

The  figure  of  this  bone,  as  its  name  imports,  resembles  the 
Greek  letter  v.  In  its  natural  situation,  the  central  and  convex 
part  is  anterior,  and  the  lateral  portions  extend  backwards. 

The  central  part  is  called  the  body,  and  the  lateral  portions 
the  cornua. 

The  body  is  broad  and  its  upper  edge  bent  inwards,  so  that 
the  external  surface  is  convex,  vertically,  as  well  as  horizon- 
tally. On  this  surface  is  a  horizontal  ridge:  the  muscles 
which  proceed  from  the  lower  jaw  are  generally  inserted 


REGIONS  OF  THE  SKULL.  119 

above    this    ridge,   and    the     muscles    from    the   sternum     and 

scapula  below  it. 

The  internal  or  posterior  surface  of  the  body  is  very  concave. 
The  cornua,  in   young  subjects,  are  distinct  from   the7  body 

of  the  bone,  and  joined  to  it  by  cartilages :  near  the  body  of 

the  os  hyoides  they  are  flat ;  but  their  figure  soon  changes,  and 

they  terminate  on  each  side  in  a  small  tubercle. 

Fig.  .21.*  On   the  upper  edge  of  the  bone, 

where  the  cornua  unite  to  the  body, 
is  a  process,  equal  in  size  to  a  small 
grain  of  wheat,  which  has  a  direction 
upwards  and  backwards ;  this  is 
called  the  appendix,  or  lesser  cornu 
of  the  os  hyoides :  from  it  proceeds 

a   ligament   which    is    attached    to  the  styloid    process  of  the 

temporal  bone,  and  is  sometimes  ossified. 

The  basis  of  the  tongue  is  attached  to  the  os  hyoides,  and 

the  motions  of  the  bone  have  a  particular  reference  to  those  of 

that  organ  ;  but  they  will  be  better  understood  when  the  parts 

with  which  it  is  connected  have  been  described. 

Regions  of  the  Skull. 

— The  skull  considered  as  a  whole  may  be  divided  for  the 
occasional  purpose  of  defining  the  seats  of  injuries  into  four 
regions. 

— The  superior  region  or  vertex,  is  bounded  anteriorly  by  the 
frontal  eminences  ;  on  each  side  by  the  temporal  ridges  and 
parietal  eminences,  and  behind  by  the  superior  curved  line  of 
the  occipital  bone  and  occipital  protuberance.  The  anterior 
region  or  face  as  seen  in  Fig.  28,  is  somewhat  oval  in  contour, 
irregular  in  surface  and  excavated  for  the  reception  of  two 
principal  organs  of  sense,  the  eye  and  the  nose.  It  is  formed  in 
part  by  the  frontal  bones  and  by  the  bones  of  the  face.  It  is 
bounded  above  by  the  frontal  protuberances,  below  by  the 

*  The  os  hyoides  seen  from  before.  1.  The  anterior  convex  side  of  the  body. 
2.  The  great  cornu  of  the  left  side.  3.  The  lesser  cornu  of  the  same  side.  The 
cornua  were  ossified  to  the  body  of  the  bone  in  the  specimen  from  which  the 
figure  was  drawn. 


120 


ORBIT    OF    THE    EYE, 


chin,    and     on    the    sides     by    the    malar   bones. — If    a    per- 
Fig.  28.*  pendicular   line   be    drawn    down 

the  face  from  the  inner  third  of 
the  supra-orbital  ridge  to  the  inner 
third  of  the  body  of  the  lower 
jaw,  it  will  intersect  three  fora- 
mina, the  supra-orbital,  infra- 
orbital,  and  mental,  each  giving 
passage  to  one  of  the  facial 
branches  of  the  fifth  nerve,  the 
common  seats  of  facial  neu- 
ralgia. 

The  lateral  region  or  side  of 
the  head,  comprises  the  tem- 
poral and  zygomatic  fossae  and 
the  mastoid  portion  of  the  tem- 
poral bone. 

— The  inferior  region  or  base  of  the  skull,  is  very  irregular 
and  presents  an  internal  or  cerebral  and  an  external  or  basilar 
surface. 

— From  the  importance  of  the  vessels  and  nerves  which 
traverse  it,  this  region  requires  to  be  particularly  studied. — 


An  acquaintance  with  the  individual  bones  which  compose  the  head  is  princi- 
pally useful,  as  it  leads  to  a  perfect  understanding  of  the  whole  structure,  of 
which  each  bone  is  but  a  small  part. 

This  structure  comprises  the  cavities  which  contain  the  brain  and  the  most 
important  organs  of  sense,  as  well  as  the  foramina  subservient  to  them,  which 
are  of  so  much  importance  in  the  practice  of  medicine  and  surgery,  and  also 
in  physiology,  that  the  following  descriptions  are  subjoined. 

Orbit  of  the  Eye. 

The  figure  of  this  cavity  is  that  of  a  quadrangular  pyramid 
with  its  angles  rounded ;  so  it  resembles  a  cone,  the  bottom 
being  the  apex  and  the  orifice  the  base. 

*  A  front  view  of  the  skull.  1.  The  anterior  portion  of  the  frontal  bone. 
2.  The  nasal  protuberance.  3.  The  supra-orbital  ridge.  4.  The  optic  foramen. 
5.  The  sphenoidal  fissure.  6.  The  spheno-maxillary  fissure.  7.  The  lachrymal 
fossa  in  the  lachrymal  bones,  the  commencement  of  the  nasal  duct.  The  figures 
4,  5,  6,  7.  are  within  the  orbit.  8.  The  opening  of  the  anterior  nares,  divided 
into  two  parts  bythevomer:  the  number  is  placed  upon  the  latter.  9.  The 
infra-orbital  foramen.  10.  The  malar  bone.  11.  The  symphysis  of  the  lower 


ORBIT    OF    THE    EYE.  121 

The  diameter  of  the  cavity  passes  obliquely  outward  from 
the  apex  behind.  As  the  figure  is  irregular,  the  side  next  the 
nose  does  not  partake  of  this  general  obliquity,  but  extends  in  a 
straight  direction  from  behind  forwards. 

The  orbit  is  somewhat  contracted  at  its  orifice,  and  enlarged 
immediately  within.  The  form  of  the  orifice  is  rather  oval,  as 
the  transverse  diameter  is  longer  than  the  vertical.  Seven  bones 
are  concerned  in  the  formation  of  this  cavity ;  the  os  frontis  and 
a  portion  of  the  lesser  wing  of  the  sphenoid  bone  above,  the  os 
planum  of  the  ethmoid,  the  os  unguis,  and  the  nasal  process  of 
the  upper  maxillary  bone,  and  the  os  palati  below  ;  the  osmalae, 
and  orbitar  plate  of  the  sphenoid  bone,  on  the  outside. 

On  the  upper  surface  is  the  depression  for  the  lachrymal 
gland  ;  and  at  the  orifice  is  the  notch  or  foramen  for  the  supra- 
orbitary  vessels,  See.,  which  have  already  been  mentioned. 

On  the  inner  surface  are  two  longitudinal  sutures,  which 
connect  the  os  planum  and  the  os  unguis  to  the  os  frontis  above, 
and  the  os  maxillare  below.  In  the  upper  suture  are  the  two 
internal  orbitary  foramina  mentioned  in  the  description  of  the 
os  frontis,  the  anterior  of  which  transmits  a  fibre  of  the  ophthal- 
mic nerve,  with  an  artery  and  vein ;  the  posterior  transmits  only 
an  artery  and  vein.  There  are  also  two  smaller  vertical  sutures 
on  each  side  of  the  os  unguis.  On  the  anterior  part  of  this 
inner  surface  is  the  ridge  of  the  os  unguis,  and  the  grooves  for 
accommodating  the  lachrymal  sac,  which  passes  into  the  canal 
of  the  same  immediately  below. 

On  the  lower  surface  is  the  aforesaid  canal,  formed  by  the 
nasal  and  orbitar  process  of  the  upper  maxillary  bone,  and  that 
part  of  the  os  unguis  which  is  anterior  to  the  ridge.  On  the 
posterior  part  of  this  surface  is  a  groove  which  proceeds  for- 
wards, and  penetrating  into  the  bone,  becomes  a  canal  that 
terminates  in  the  infra-orbitar  foramen  ;  this  groove  in  the  bone  is 
made  a  canal  by  the  periosteum.  The  thin  plate  which  forms  this 

jaw.  12.  The  mental  foramen.  13.  The  ramus  of  the  lower  jaw.  14.  The 
parietal  bone.  15.  The  coronal  suture.  16.  The  temporal  bone.  17.  The  squa- 
mous  suture.  18.  The  upper  part  of  the  great  ala  of  the  sphenoid  bone.  19. 
The  commencement  of  the  temporal  ridge.  20.  The  zygoma  of  the  temporal 
bone,  assisting  to  form  the  zygomatic  arch.  21.  The  mastoid  process. 
11 


122  CAVITIES    OF    THE    NOSE. 

surface  is  the  partition  between  the  antrum  maxillare  and  the 
orbit  of  the  eye,  and  is  more  or  less  absorbed  in  those  cases  where 
polypi  of  the  antrum  maxillare  occasion  a  protrusion  of  the  eye. 

The  external  surface,  formed  by  the  malar  bone  and  the 
orbitar  plate  of  the  sphenoid,  is  almost  flat.  In  the  posterior 
part  of  the  orbit  it  is  bounded  by  two  large  fissures,  which  are 
now  to  be  described. 

In  the  posterior  part  of  the  orbit  are  three  apertures.  The  optic 
foramen,  the  sphenoidal  fissure,  and  the  spheno-maxillary  fissure. 

The  optic  foramen  opens  almost  at  the  bottom  of  the  orbit  on 
the  inside  ;  its  direction  is  forwards  and  outwards. 

The  sphenoidal  fissure,  formed  principally  by  the  lesser  and 
greater  wings  of  the  sphenoidal  bone,  begins  at  the  bottom  of 
the  orbit,  and  extends  forward,  upward,  and  outward.  It  is 
broad  at  the  commencement,  and  gradually  diminishes  to  a  fissure. 
This  fissure  opens  directly  into  the  cavity  of  the  cranium,  and 
admits  the  passage  of  the  third,  fourth,  sixth,  and  one  branch  of 
the  fifth  pair  of  nerves,  and  an  artery,  and  a  vein. 

The  spheno-maxillary  fissure  commences  also  at  the  bottom 
of  the  orbit,  and  extends  forward,  outward,  and  downward, 
between  the  maxillary  bone  and  the  orbitar  plate  of  the  sphe- 
noid, from  the  body  of  the  sphenoid  to  the  malar  bone.  This 
fissure  opens  from  the  orbit  directly  into  the  zygomatic  fossa.  In 
the  recent  subject  it  is  closed,  and  only  transmits  the  infra-orbi- 
tary  nerve  and  vessels,  and  a  small  branch  of  the  superior 
maxillary  nerve. 

The  Cavities  of  the  Nose. 

These  cavities,  which  are  separated  from  each  other  by  the 
septum  narium,  are  contained  between  the  cribriform  plate  of 
the  ethmoid  and  the  palatine  process  of  the  upper  maxillary  and 
palate  bones,  and  between  the  anterior  and  posterior  nares. 
They  are,  therefore,  of  considerable  extent  in  these  directions ; 
but  the  distance  from  the  septum  to  the  opposite  side  of  the 
nose  is  so  small,  that  each  cavity  is  very  narrow. 

The  upper  surface  of  each  cavity  consists  of  that  portion  of 
the  cribriform  plate  of  the  ethmoid  which  is  between  the  septum 
and  the  cellular  portions.  Anterior  to  this,  each  cavity  is 


CAVITIES    OF    THE    NOSE.  123 

bounded  by  the  internal  surface  of  the  os  nan  of  its  respective 
side ;  and  posterior  to  it,  by  the  anterior  surface  of  the  body  of 
the  sphenoid  bone.  These  anterior  and  posterior  surfaces  form 
obtuse  angles  with  the  upper  surface  of  the  nose,  and^are  im- 
mediately above  the  openings  called  anterior  and  posterior  nares. 
The  anterior  surface  partakes  of  the  figure  of  the  os  nasi ;  the 
upper  surface  has  the  perforations  of  the  cribriform  plate  ;  the 
posterior  surface  has  an  opening,  equal  in  diameter  to  a  small 
quill,  that  leads  into  the  sphenoid  cell,  and  is  also  broader  than 
the  anterior  or  superior  surface. 

The  internal  surface,  formed  by   the  septum    of  the   nose, 
which  is  composed  of  the  vomer,  the  nasal  plate  of  the  ethmoid, 
and  the  cartilaginous  plate,  is  flat,  but  rather  inclined  to  one  side  or 
the  other,  so  as  to  make  a  difference  in  the  size  of  the  nasal  cavities. 
Fig.  29.*  The  external  surface  is  very 

irregular;  it  is  formed  by  the 
cellular  portions  of  the  ethmoid; 
by  a  small  portion  of  the  os 
unguis ;  by  the  upper  maxillary 
bone ;  the  os  turbinatum  infe- 
rius ;  the  os  palati ;  and  the 
internal  pterygoid  process  of 
the  05  sphenoides.  The  upper 
part  of  this  surface  is  formed 
by  the  internal  surface  of  the 
cellular  portions  of  the  ethmoid, 

*  Fig.  29.  A  longitudinal  section  of  the  nasal  fossa  (taken  from  Wilson) — 
made  to  the  right  side  of  the  vomer,  and  the  bony  septum  removed  in  order  to 
exhibit  the  external  wall  of  the  left  nasal  fossa.  1.  Os  frontis — 2.  Os  nasi.  3. 
The  cristagalli  process  of  the  ethmoid.  The  groove  between  fig.  1  &c  3,  is  the 
lateral  boundary  of  the  foramen  caecum.  4.  The  cribriform  plate  of  the  ethmoid. 
5.  Part  of  the  sphenoidal  cells.  6.  The  basilar  portion  of  the  sphenoid  bone. 
Bones  2,  4,  &  5.  form  the  superior  boundary  of  the  nasal  fossa.  7,  7.  The 
articulating  surface  of  the  palatine  process  of  the  superior  maxillary  bone. 
The  groove  between  7,  7.  is  the  lateral  half  of  the  incisive  canal,  and  the  dark 
aperture  in  the  groove  the  inferior  termination  of  the  left  naso  palatine  canal. 
8.  The  nasal  spine.  9.  The  palatine  process  of  the  palate  bone.  a.  The  superior 
turbinated  bone  marked  by  grooves  and  apertures  for  filaments  of  the  olfactory 
nerve,  b.  The  superior  meatus.  c.  A  probe  passed  into  the  posterior  ethmoidal 
cells,  d.  The  opening  of  the  sphenoidal  cells  into  the  superior  meatus.  e.  The 
•spheno-palatine  foramen.  /.  The  middle  turbinated  bone,  g,  g.  The  middle 
meatus.  h.  A  probe  passed  into  the  infundibular  canal,  leading  from  the  frontal 


124  CAVITIES    OF    THE    NOSE. 

which  have  been  described  at  page  76.  It  extends  from  the  sphe- 
noid bone,  very  near  to  theossanasi ;  and  is  uniformly  flat  and  rough. 

About  the  middle  of  it  begins  a  deep  groove,  which  penetrates 
into  the  cellular  structure  of  the  ethmoides,  and  passes  obliquely 
downwards  and  backwards.  At  the  upper  end  of  this  groove  is 
the  foramen  by  which  the  posterior  ethmoidal  cells  communicate 
with  the  nasal  cavity. 

This  is  the  upper  channel  &r  meatus  of  the  nose.  At  the 
posterior  end  of  it  is  a  large  foramen  formed  by  the  nasal  plate 
of  the  os  palati  and  the  pterygoid  process  of  the  os  sphenoides, 
and  therefore  called  pterygo  or  spheno-palatine  foramen.  It 
opens  externally,  and  transmits  a  nerve  and  an  artery  to  the  nose. 

Below  the  meatus  is  the  upper  spongy  bone,  which  presents  a 
convex  surface ;  its  lower  edge  is  rolled  up  and  not  connected 
with  the  parts  about  it.  This  spongy  bone  covers  a  foramen  in 
the  ethmoid  bone,  by  wbich  its  anterior  cells  and  the  frontal 
sinuses  communicate  with  the  nose. 

Below  this  spongy  bone  is  the  middle  channel,  or  meatus  of 
'the  nose.  The  channel  extends  from  the  anterior  to  the  poste- 
rior part  of  the  cavity.  It  is  very  deep,  as  it  penetrates  to  the 
maxillary  bone.  The  cells  of  the  ethmoid  are  above  it;  the 
inferior  turbinated  bone  below  it ;  and  the  upper  spongy  bone 
projects  over  it.  In  this  channel  is  the  opening  of  the  great 
cavity  of  the  upper  maxillary  bone.  At  the  anterior  extremity 
of  it  is  a  small  portion  of  the  os  unguis,  which  intervenes  between 
the  nasal  process  of  the  upper  maxillary  bone  and  the  cells  of 
ihe  ethmoid,  and  continues  down  to  the  lower  spongy  bone. 

The  lower  spongy  bone  is  nearly  horizontal,  and  very  conspi- 

sinuses  and  anterior  ethmoid  cells ;  the  triangular  aperture  immediately  above 
the  letter  is  the  opening  of  the  maxillary  sinus,  i.  The  inferior  turbinated  bone. 
Jc,  k.  The  inferior  meatus.  I,  L  A  probe  passing  up  the  nasal  duct,  showing  the 
direction  of  that  canal.  The  anterior  letters  g,  /;,  are  placed  on  the  superio? 
maxillary  bone,  the  posterior  on  the  palate  bone.  m.  The  internal  pterygoid 
plate,  n.  The  hamular  process.  0.  The  external  pterygoid  plate,  p.  The  situa- 
tion of  the  opening  of  the  Eustachian  tube.  q.  The  posterior  palatine  foramina, 
the  letter  is  placed  on  the  hard  palate,  r.  The  roof  of  the  left  orbit.  5.  The 
optic  foramen,  t.  The  groove  for  the  last  turn  of  the  internal  carotid  artery 
converted  into  a  foramen  by  the  development  of  an  osseus  communication  be- 
tween the  anterior  and  middle  clinoid  processes,  v.  The  sella  turcica.  z.  The 
posterior  clinoid  process. — 


THE  CAVITY  OF  THE  CRANIUM.  125 

cuous.  It  extends  almost  from  one  opening  of  the  nose  to  the 
other.  Under  this  bone  is  the  third  and  largest  channel  or  infe- 
rior meatus  of  the  nose.  It  is  made  large  by  an  excavation  of 
the  upper  maxillary  bone,  particularly  at  the  anterior  part.  It 
affords  a  direct  and  very  easy  passage  to  the  posterior  opening  of 
the  nose  and  the  throat. 

Near  the  anterior  extremity  of  this  meatus  is  the  lower  orifice 
of  the  lachrymal  duct,  which  is  so  situated  that  a  probe  properly 
curved  can  be  readily  passed  into  it  through  the  nostril. 

There  are,  then,  four  foramina  on  each  side,  which  form  com- 
munications between  the  cavities  of  the  nose  and  the  adjacent 
cells,  viz. 

One  in  the  upper  meatus,  which  leads  to  the  posterior  ethmoid 
cells. 

A  second  in  the  middle  meatus,  which  leads  to  the  anterior 
ethmoid  cells  and  the  frontal  sinuses. 

A  third  in  the  same  meatus,  which  opens  into  the  maxillary 
sinus. 

A  fourth  in  the  anterior  surface  of  the  body  of  the  sphenoidal 
bone,  which  opens  into  the  sphenoidal  sinus. 

To  these  must  be  added  the  opening  of  the  lachrymal  canal. 

It  will  be  moat  useful  to  the  student  of  anatomy,  after  placing  three  or  four  of 
the  uppermost  cervical  vertebrae  in  their  natural  situation,  to  take  a  view  of 

The  Cavity  between  the  spine  and  the  posterior  Nares,  which 
is  bounded  above,  by  the  cuneiform  process,  passing  obliquely 
upward  and  forward  ;  laterally,  by  soft  parts  not  yet  described  ; 
behind,  by  the  bodies  of  the  cervical  vertebrae  ;  and  before,  by 
the  posterior  nares,  each  of  which  is  oblong  in  form,  rounded 
above,  flat  below,  and  separated  from  the  other  by  a  thin  parti- 
tion, the  vomer. 

The  Cavity  of  the  Cranium. 

The  upper  concave  surface  of  this  cavity  corresponds  with 
the  figure  of  the  cranium.  The  ridge  in  it  for  supporting  the  fal- 
ciform process  of  the  dura  mater,  the  groove  made  by  the  longi- 
tudinal sinus,  the  impressions  of  the  arteries,  and  the  pits  made 
by  the  convolutions  of  the  brain,  are  particularly  to  be  noticed. 
11* 


126 


THE    INTERNAL    BASIS    OF    THE    CRANIUM. 


The  Internal  Basis  of  the  Cranium 

Is  much  more  important.  It  is  divided  into  three  fossae  on  each 
side  ;  the  anterior  of  these  are  most  superficial,  and  the  posterior 
the  deepest.  The  bottoms  of  the  anterior  foss&  are  formed  by 
the  orbitar  processes  of  the  osfrontis,  and  consequently  are  con- 
vex ;  between  them  is  the  cribriform  plate  of  the  ethmoid,  which 
is  commonly  sunk  below  the  adjoining  surface.  The  crista  galli 
is  very  conspicuous ;  and  the  foramen  caecum  can  almost  always 
be  seen.  The  crista  galli  is  evidently  the  beginning  of  the  pro- 
minent ridge,  which  continues  on  the  os  frontis,  and  supports  the 
falx  of  the  dura  rnater.  The  posterior  margins  of  these  fossae 
are  formed  by  the  lesser  wings  of  the  sphenoid  bone. 

The   middle  fossa    are    formed   by   the  great  wings  of  the 
sphenoidal    bone,  and   by   the  squamous  and   petrous   portions 
of  the   temporal   bone.      They   are   lower   than    the    anterior, 
and    higher  than  the    posterior  fossae.     The   projection   of  the 
Fig.    30.*  margin    of    the    anterior   fossae 

into  these  cavities,  corresponds 
with  the  separation  between 
the  anterior  and  middle  lobes 
of  the  brain.  The  suture  be- 
tween the  sphenoidal  and  tem- 
poral bones  is  evident  in  these 
fossae.  The  upper  surface  of 
the  body  of  the  sphenoid  bone, 
or  the  sella  turcica  is  between 
them ;  and  all  the  peculiarities 
of  its  surface  are  very  conspi- 
cuous. The  first  five  foramina 
of  the  sphenoidal  bone  can  IK- 
easily  ascertained,  and  also,  the 
anterior  foramen  lacerurn  and 

*  The  cerebral  surface  of  the  base  of  the  skull.  1.  One  side  of  the  anterior 
fossa  j  the  number  is  placed  on  the  roof  of  the  orbit,  formed  by  the  orbital  plate 
of  the  frontal  bone.  2.  The  lesser  wing  of  the  sphenoid.  3.  The  crista  galli. 
4.  The  foramen  caecum.  5.  The  cribriform  lamella  of  the  ethmoid.  6.  The 
processus  olivaris.  7.  The  foramen  opticum.  8.  The  anterior  clinoid  process. 
9.  The  carotid  groove  upon  the  side  of  the  sella  Turcica,  for  the  internal  carotid 
artery  and  cavernous  sinus.  10,  11,  12.  The  middle  fossa  of  the  base  of  the 
skull.  10.  Marks  the  great  ala  of  the  sphenoid.  11.  The  squamous  portion  of 


THE    INTERNAL    BASIS    OF    THE    CRANIUM.  127 

termination  of  the  foramen  caroticum,  with  the  impressions 
made  by  the  carotid  arteries  on  the  sides  of  the  sella  turcica. 
The  petrous  portions  of  the  temporal  bones  are  the  posterior 
boundaries  of  the  middle  fossae.  Their  oblique  direction, 
inwards  and  forwards,  is  particularly  remarkable;  being  formed 
like  triangular  pyramids.  Two  of  their  sides  are  in  the  cavity 
of  the  cranium  ;  one,  which  is  anterior,  forms  a  portion  of  the 
middle  fossa  ;  and  the  other  forms  a  part  of  the  posterior  fossa. 
The  edge  between  them  is  very  prominent,  and  has  the  tento- 
rium  or  horizontal  process  of  the  dura  mater  attached  to  it.  On 
the  anterior  surface,  in  the  middle  fossa,  may  be  traced  the 
groove,  and  the  foramen  for  the  Vidian  nerve. 

The  posterior  fossae  are  larger  as  well  as  deeper  than  the 
other  two.  Their  boundaries  are  well  defined  by  the  edges  of 
the  petrous  bones  above  mentioned,  and  by  the  grooves  of  the 
horizontal  parts  of  the  lateral  sinuses.  These  fossae  are  nearly 
separated  from  the  general  cavity  by  the  tentorium,  which  is 
attached  to  the  edge  of  the  petrous  bone  and  also  to  the  edge 
of  the  horizontal  part  of  the  groove  for  the  lateral  sinuses.  On 
the  tentorium  lie  the  posterior  lobes  of  the  cerebrum ;  and  under 
it,  in  these  fossae,  is  the  cerebellum. 

These  fossae  may  be  considered  as  one  great  cavity,  which  is 
circular  behind,  and  somewhat  angular  before.  The  angular 
surfaces  are  formed  by  the  posterior  sides  of  the  petrous  portions. 
Between  them,  is  the  oblique  surface  of  the  cuneiform  process  of 
the  occipital  bone,  which  descend  to  the  great  foramen.  On  the 
surface  of  each  petrous  bone  is  the  meatus  auditorius  internus, 
and  the  orifice  of  the  aqueduct  of  the  vestibule.  Behind  the 
petrous"  portion,  the  groove  for  the  lateral  sinus  is  very  conspicu- 
ous ;  it  terminates  in  the  posterior  foramen  lacerum,  which  is 
evidently  formed  by  the  temporal  and  the  occipital  bones.  At 

the  temporal  bone.  12.  The  petrous  portion  of  the  temporal.  13.  The  sella 
Turcica.  14.  The  basilar  portion  of  the  sphenoid  bone,  surmounted  by  the  pos- 
terior clinoid  processes.  15.  The  foramen  rotundum.  16.  'the  foramen  ovale. 
17.  The  foramen  spinosum  ;  the  small  irregular  opening  between  17  and  12  is 
the  hiatus  Fallopii.  18.  The  posterior  fossa  of  the  base  of  the  skull.  19,  19. 
The  groove  for  the  lateral  sinus.  20.  The  ridge  upon  the  occipital  bone,  which 
gives  attachment  to  the  falx  cerebelli.  21.  The  foramen  magnum.  22.  The 
meatus  auditorius  internus,  23.  The  jugular  foramen. 


128 


EXTERNAL    BASIS    OF    THE    SKULL. 


the  anterior  part  of  this  foramen  is  most  commonly  a  small  bony 
process,  which  separates  the  eighth  pair  of  nerves  from  the 
internal  jugular  vein,  as  they  pass  out  here. 

The  anterior  condyloid  foramen  for  the  passage  of  the  ninth 
pair  of  nerves,  appears  in  the  surface  of  the  great  occipital  hole, 
immediately  below  the  foramen  lacerum.  From  the  back  part 
of  this  hole  the  spine,  which  forms  the  lower  limb  of  the  cross, 
passes  up;  and  on  each  side  of  it  are  the  great  depressions 
which  accommodate  the  two  lobes  of  the  cerebellum. 

External  Basis  of  the  Skull. 

t 

The  external  surface  of  the  base  of  the  skull  is  very  irre- 
gular. When  the  head  is  inverted,  we  see  the  external  protu- 
berances of  the  as  occipitis,  formerly  described.  The  mastoid 
processes  of  the  ossa  temporum  are  on  the  same  transverse 
line  with  the  great  foramen  of  the  os  occipitis  ;  but  the  foramen 
being  larger  extends  farther  forward.  On  the  inside  of  the 
mastoid  process,  the  fissure  for  the  digastric  muscle  is  very  con- 
spicuous, and  also  the  suture  between  the  mastoid  process  and 
the  occipital  bone. 

Fig.  31.*  The  oblique  direction  of 

the  occipital  condyles  and 
the  slanting  position  of 
their  articulating  surfaces 
are  particularly  striking. 
The  posterior  condyloid 
foramina  for  the  cervical 
veins,  and  the  anterior  for 
the  ninth  pair  of  nerves, 
are  also  in  view.  The 
position  of  the  cuneiform 
process  of  the  os  occipitis 
is  by  no  means  horizontal, 
but  extends  forwards  and 
upwards.  The  petrous  or 
pyramidal  portion  of  the 
temporal  bone  commence? 

*  The  external  or  basilar  surface  of  the  base  of  the  skull.     1,1.  The  hard 
palate.    The  figures  are  placed  upon  the  palate  processes  of  the  superior  maxil- 


BASIS    OF    THE    SKULL.  129 

between  the  mastoid  process  and  the  condyle  of  the  lower  jaw, 
and  extends  obliquely  forwards  and  inwards,  having  the 
occipital  bone  behind  it,  and  the  glenoid  cavity  or  fossae  and 
the  os  sphenoides  before  it.  At  the  commencement,  the 
surface  of  the  petrous  portion  is  not  horizontal,  but  oblique, 
sloping  into  the  glenoid  cavity  with  a  sharp  edge  downwards. 
This  edge  in  some  cases  is  curved  so  as  to  surround  the  basis 
of  the  styloid  process,  which  arises  in  contact  with  it,  and 
projects  downwards,  on  each  side  of  the  vertebrae.  Between 
the  mastoid  and  styloid  process,  is  the  foramen  stylo-mastoi- 
deum.  On  the  inside  of  the  styloid  process,  and  rather  anterior 
to  it,  is  the  foramen  lacerum  posterius,  for  the  internal  jugular 
vein,  the  eighth  pair  of  nerves,  &tc.  This  foramen  passes 
obliquely  backwards  and  upwards,  and  is  bounded  behind  by 
the  jugular  process  of  the  os  occipitis,  which  bone  seems  to 
contribute  most  to  its  formation.  Very  near  to  this  hole  on  the 
inside  is  the  anterior  condyloid  foramen ;  and  rather  anterior  to 
it  is  the  opening  of  the  carotid  canal,  which  forms  a  curve  in  the 
bone  as  it  passes  upwards,  inwards,  and  forwards. 

From  the  foramen  lacerum  posterius,  the  suture  between 
the  cuneiform  process  of  the  occipital  and  the  petrous  portion 
of  the  temporal  bone,  extends  to  the  foramen  lacerum  anterius 
of  the  base  of  the  cranium  ;  which  is  closed  by  cartilage  in 
the  recent  subject,  but  is  of  an  irregular  and  rather  triangular 
form  in  the  macerated  head ;  this  hole  is  formed  by  the 
occipital,  sphenoidal,  and  petrous  bones.  The  suture  or 
connexion  between  the  petrous  bone  and  the  os  sphenoides,  is 

lary  bones.  2.  The  incisive,  or  anterior  palatine  foramen.  3.  The  palate  pro- 
cess of  the  palate  hone.  The  large  opening  near  the  figure  is  the  posterior 
palatine  foramen.  4.  The  palate  spine  ;  the  curved  line  upon  which  the  num- 
ber rests,  is  the  transverse  ridge.  5.  The  vomer  dividing  the  openings  of  the 
posterior  nares.  6.  The  internal  pterygoid  process.  7.  The  scaphoid  fossa.  8. 
The  external  pterygoid  plate.  The  interval  between  6  and  8  (left  side  of  the 
figure),  is  the  pterygoid  process.  9.  The  zygomatic  fossa.  10.  The  basilar 
process  of  the  occipital  bone.  11.  The  foramen  magnum.  12.  The  foramen 
ovale.  13.  The  foramen  spinale.  14.  the  glenoid  fossa.  15.  The  meatus  audi- 
torius  externus.  16.  The  foramen  lacerum  basis  cranii.  17.  The  carotid  fora- 
men of  the  left  side.  18.  The  foramen  lacerum  posterius,  or  jugular  foramen. 
19.  The  styloid  process.  20.  The  stylo-mastoid  foramen.  21.  The  mastoid 
process.  22.  One  of  the  condyles  of  the  occipital  bone.  23.  The  posterior 
condyloid  foramen. 


130  BASIS    OF    THE    SKULL. 

continued  on  the  anterior  side  of  the  petrous  bone,  from  the 
fissure  of  the  glenoid  cavity  to  the  anterior  foramen  lacerum. 
The  styloid  process  of  the  os  sphenoides,  which  is  seldom  more 
than  four  lines  in  length,  appears  at  the  edge  of  this  suture. 
On  the  inside  of  the  glenoid  cavity,  and  on  the  inside  of  this 
process,  in  the  suture  formed  between  the  petrous  and  sphenoid 
bones,  is  the  bony  orifice  of  the  Eustachian  tube. 

The  foramen  spinale,  for"  the  middle  artery  of  the  dura 
mater,  is  at  a  very  small  distance  from  the  Eustachian  tube, 
immediately  anterior  to  it ;  and  at  a  small  distance  on  the 
inside  and  front  of  this  foramen  is  the  foramen  ovale,  for  the 
inferior  maxillary  nerve,  or  the  third  branch  of  the  fifth  pair. 
— Proceeding  from  before  backwards  the  base  of  the  skull  apper- 
taining to  the  face  is  seen  to  be  formed  by  the  palate  processes 
of  the  superior  maxillary  and  palate  bones  ;  by  the  vomer  ;  the 
pterygoid  spinous  processes,  and  part  of  the  body  of  the  sphenoid. 
— The  roof  of  the  mouth  as  seen  at  1,  3,  Fig.  31,  is  constituted 
by  the  palatine  processes  of  the  superior  maxillary  and  palate 
bones.  The  transverse  suture  which  separates  them  is  well 
seen  on  the  left  side  of  the  cut.  In  the  longitudinal  suture 
and  directly  behind  the  front  incisor  teeth,  2,  is  the  incisive  or 
anterior  palatine  foramen,  the  inferior  opening  of  the  naso- 
palatine  canal,  which  lodges  the  ganglion  of  Cloquet  (naso- 
palatine)  and  transmits  the  anterior  palatine  nerves.  The 
posterior  palatine  foramina,  are  placed  near  the  posterior  angles 
of  the  hard  palate,  for  the  purpose  of  transmitting  to  the  palate 
the  blood-vessels  and  nerves  of  that  name.  The  opening  of 
the  larger  foramen  is  seen  near  3,  Fig.  31.  On  the  innetf  side  of 
this  foramen  is  seen  the  transverse  ridge  upon  which  is  inserted 
the  expanded  tendon  of  the  tensor  palati  muscle.  The 
rounded  crescentic  border,  which  terminates  posteriorly  each 
half  of  the  hard  palate,  gives  attachment  to  the  velum  pendu- 
lum palati ;  and  in  the  middle  line  4,  is  seen  the  palate  spine 
from  which  is  hung  the  azygos  uvuloe  muscle.  The  posterior 
nares  is  seen  immediately  above  divided  by  the  vorner,  5,  and 
bounded  externally  by  the  internal  pterygoid  processes,  6.  By 
the  side  of  the  shelving  base  of  the  vomer  and  partly  formed 
by  it  are  the  pterygo-palatine  canals,  which  transmit  the 


SIDE    OF    THE    HEAD.  131 

ptery go-palatine  arteries.  The  external  pterygoid  process  is 
seen  at  8,  and  between  the  two  processes,  is  the  pterygoid 
fossa,  which  is  occupied  by  the  internal  pterygoid  muscle. 
On  the  outer  side  of  the  external  pterygoid  process  i^  the 
zygomatic  fossa.  The  internal  pterygoid  process  is  long  and 
narrow,  having  at  its  apex  the  hamulus,  and  at  its  base  the 
scaphoid  fossa  from  which  arises  the  circumflexus  or  tensor 
palati  muscle. — 

Side  of  the  Head. 

Those  portions  of  the  side  of  the  head  which  are  formed  by 
the  frontal,  parietal  and  occipital  bones,  and  by  the  squamous 
part  of  the  temporal,  require  no  explanation  here  ;  but  the 
region  which  is  behind  the  malar  and  upper  maxillary  bone, 
and  within  the  zygomatic  processes  of  the  temporal  and  malar 
bones,  which  comprises  part  of  the  temporal  and  zygomatic 
fossae  of  some  anatomists,  is  both  important  and  obscure. 

To  obtain  a  view  of  this,  the  lower  jaw  should  be  removed, 
and  the  zygoma  sawed  away,  in  one  preparation ;  and  in 
another,  the  upper  maxillary  and  palate  bones  of  one  side 
should  be  applied  in  their  natural  position,  to  the  os  sphenoides, 
without  any  of  the  other  bones. 

The  upper  part  of  this  region,  formed  by  the  sphenoidal, 
frontal  and  malar  bones,  is  made  concave  by  the  form  of  the 
external  angular  part  of  the  os  frontis  and  of  the  os  malse ; 
which  projects  backwards  so  as  to  cover  a  large  portion  of  it. 

The  lower  part  is  formed  principally  by  the  external  surface 
of  the  pterygoid  process  of  the  sphenoid  bone,  and  by  the 
posterior  surface  of  the  upper  maxillary.  Between  the  lower 
end  of  the  pterygoid  process  and  the  upper  maxillary  bone,  a 
small  portion  of  the  os  palati  intervenes  ;  but  in  many  adult 
subjects  it  is  not  to  be  distinguished  from  the  other  bones.  At 
this  place,  the  pterygoid  process  and  these  bones  appear  to  be 
in  close  contact ;  but  as  they  pass  upwards  they  recede  from 
each  other  so  as  to  form  a  considerable  aperture,  which 
continues  the  whole  length  of  the  pterygoid  process.  This 
fissure,  which  may  be  called  pterygo-palatine  or  pterygo- 
maxillary,  would  open  into  the  posterior  part  of  the  cavity  of 


132  THE  FORM  OF  THE  CRANIUM. 

the  nose,  if  the  nasal  plate  of  the  os  palati  did  not  intervene ; 
this  plate  forms  a  partition,  which  separates  the  nose  from  this 
fissure :  and  the  spheno-palatine  foramen,  formed  principally 
by  it,  transmits  a  nerve  and  blood-vessels  to  the  nose. 

The  fissure  is  vertical :  at  the  back  of  the  orbit,  it  unites 
with  the  spheno-maxillary  fissure  of  the  orbit,  which  is  almost 
horizontal,  and  at  the  place  of  their  junction,  the  sphenoidal,  or 
upper  fissure  of  the  orbit,  opeffs  also. 

The  foramen  rotundum,  which  transmits  the  second  branch 
of  the  fifth  pair,  or  the  upper  maxillary  nerve,  is  likewise 
situated  near  this  place  ;  and  when  the  upper  maxillary,  the 
sphenoidal,  and  the  palate  bones  are  in  their  natural  situation, 
the  distribution  of  the  branches  of  this  important  nerve  can  be 
easily  understood :  for  the  same  view  presents  the  course  of  its 
various  branches  ;  viz.  to  the  nose,  by  the  spheno-palatine  fora- 
men ;  to  the  cavity  of  the  cranium,  by  the  pterygoid  foramen  ; 
to  the  orbit,  and  the  inferior  obitary  canal,  by  the  spheno-max- 
illary fissure ;  and  to  the  roof  of  the  mouth,  by  the  palato-max- 
illary  canal. 

The  Form  of  the  Cranium. 

The  form  of  the  cranium  is  that  of  an  irregular  oval.  The 
greatest  length  of  its  cavity  is  between  a  part  of  the  os  frontis 
above  the  crista  galli,  and  of  the  os  occipitis  above  the  centre 
of  the  crucial  ridge. 

The  greatest  breadth  is  at  about  two-thirds  of  the  distance 
from  the  first  to  the  last  of  these  positions.  This  tranverse 
diameter  touches  the  sides  of  the  cranium  near  the  posterior 
part  of  the  basis  of  the  petrous  portion  of  the  temporal  bone. 
The  difference  between  these  longitudinal  and  transverse 
diameters  varies  greatly  in  different  persons,  as  their  craniums 
approach  to  the  oval  or  round  figures. 

The  greatest  depth  of  the  cavity  is  between  the  posterior 
part  of  the  cuneiform  process  of  the  occipital  bone,  and  a  part 
of  the  cranium  which  is  nearly  over  it  about  the  middle  of  the 
sagittal  suture. 

The  figure  of  the  cranium  is  somewhat  varied  in  different 


THE  FORM  OF  THE  CRANIUM.  133 

races  of  men  ;  and  it  has  been  much  changed  by  the  particular 
management  of  several  savage  nations. 

In  North  America,  the  Choctaw  tribe  of  Indians  were  for- 
merly accustomed  tox  make  their  foreheads  perfectly  flat,  and 
sloping  obliquely  backwards.  They  have  latterly  disused  this 
practice  ;  but  one  of  their  nation,  whose  head  had  this  form,  was 
in  Philadelphia  about  the  year  1796. 

At  this  time  a  tribe  who  inhabit  a  district  of  country  near  the 
sources  of  the  Missouri  river,  are  in  the  practice  of  flattening 
both  the  frontal  and  occipital  regions  of  the  head  ;  so  that  a 
small  part  only,  of  the  middle  of  it,  remains  of  the  natural  form, 
between  these  flattened  sloping  surfaces.  J^ 

In  the  case  of  the  Choctaw  man  above-mentioned,  it  did  not 
appear  that  his  health,  or  his  intellectual  ^operations,  were  any 
way  affected  by  this  form  of  his  head. 

During  infancy,  the  cranium  sometimes  increases  to  a  preter- 
natural size,  as  disproportionate  to  the  face  as  if  it  were 
affected  by  hydrocephalus.  In  many  of  these  instances,  that 
disease  ultimately  shows  itself;  but  in  other  cases,  the  preter- 
natural increase  of  the  cranium  finally  stops  without  the  occur- 
rence of  disease  ;  and  the  disproportion  is  lessened  by  the 
increase  of  the  face  in  the  ordinary  progress  of  growth. 

In  many  cases  where  men  have  deviated  from  the  ordinary 
stature,  the  head  has  preserved  the  common  size.  It  is  therefore 
said  to  be  small  in  giants,  and  large  in  dwarfs. 

—  Many  efforts  have  been  made  to  determine  rigorously  the 
dimensions  of  the  cavity  of  the  cranium.  This  may  be  done 
with  considerable  accuracy  from  the  exterior  of  the  skull,  by 
making  allowances  for  the  various  degrees  of  development  in 
which  the  frontal  sinuses  are  found  in  different  individuals. 
The  thickness  of  the  diploe  seldom  varies  in  different  skulls 
more  than  one  or  two  lines  in  thickness.  I  have,  however, 
several  negro  skulls  in  my  possession  the  walls  of  which  are 
nearly  three-quarters  of  an  inch  in  thickness,  and  so  com- 
pact in  their  composition  as  to  present  very  little  of  the 
diploic  or  cellular  structure.  When  measured  from  the 
interior,  a  skull  of  ordinary  capacity  will  be  found  in  its 

•'"    '•   '•;   :</*rr*^'/   ^ 
~  *-    '• 


134  FACIAL  AND  OCCIPITAL  ANGLES. 

longitudinal  diameter,  (between  the  frontal  spine  and  longitudi- 
nal sulcus,)  five  inches  and  a  half;  in  its  transverse,  (between 
the  bases  of  the  petrous  portions  of  the  temporal  bones,)  four 
and  a  half;  between  the  parietal  fossae  five  inches,  and  between 
the  lesser  wings  of  the  sphenoid  bones,  three  inches  and  three- 
quarters  ;  in  the  vertical,  from  the  foramen  magnum  to  the  sagit- 
tal suture,  four  inches  and  a  half. 

— Several  plans  have  also  bean  adopted,  by  the  cranioscopists, 
to  determine  the  relative  development  of  the  cranium  (which 
is  filled  with  the  brain)  and  that  of  the  face.  The  best  known 
of  these  are  those  of  Camper,  Daubenton  and  Cuvier.  The 
facial  angle  of  Camper,  is  taken  by  extending  a  horizontal  line 
from  the  external  auditory  meatus,  on  a  line  with  the  floor  of 
the  nostril,  so  as  to  follow  nearly  in  the  direction  of  the  base 
of  the  cranium,  and  by  dropping  upon  this  a  second  from  the 
most  prominent  part  of  the  forehead  to  the  extremity  of  the 
upper  jaw.  The  area  between  them  is  the  facial  angle,  and 
will  be  the  more  acute,  in  direct  proportion  as  the  face  is  devel- 
oped in  front,  and  the  forehead  is  sloped  backwards.  This 
angle  is  of  course  larger  in  man  than  in  any  other  animal,  and 
varies  in  size  in  the  different  races  of  men.  In  a  well  formed 
white  or  Caucasian,  it  is  usually  about  80°;  in  the  Mongolian 
about  75° ;  in  Negroes  about  70° ;  in  the  different  species  of 
monkeys  it  varies  from  65°  to  30°.  As  a  test  of  the  intellectual 
capacity  of  individuals,  it  is  but  little  to  be  relied  on. 
—The  occipital  angle  of  Daubenton,  is  formed  by  drawing  two 
lines,  one  from  the  inferior  border  of  the  orbit,  to  the  anterior 
margin  of  the  occipital  foramen,  the  other  drawn  from  the 
anterior  to  the  posterior  border  of  the  occipital  foramen,  and 
extended  forwards.  The  angle  between  the  two,  is  the  occipital. 
As  the  direction  of  the  occipital  foramen  depends  upon  the 
manner  in  which  the  head  is  articulated  with  the  vertebral 
column,  it  will  be  the  larger,  the  less  favorably  the  animal  is 
constructed  for  the  upright  posture.  In  a  well-formed  Caucasian 
skull,  it  is  about  3°.  In  the  ox  it  is  about  70°.  Daubenton 
has  thus  done  for  the  posterior  part  of  the  head  what  Camper 
has  done  for  the  anterior. 


HEAD  OF  THE  FffiTUS.  135 

— Cuvier's  method  consists  in  dividing  the  skull  vertically,  and 
establishing  a  comparison  between  the  area  of  the  cranium  and 
that  of  the  face.  In  a  well-formed  Caucasian  he  finds  the  area 
of  the  cranium,  quadruple  that  of  the  face.  In  the  Mongolian 
variety,  he  found  the  area  of  the  face  had  increased  over  this 
proportion  one-tenth,  in  the  Negro,  one-fifth  ;  in  monkeys,  one- 
half.  Tiedemann  has  adopted  a  plan  of  measuring  the  capacities 
of  different  crania,  by  filling  them  with  seeds  from  the  occipital 
foramen,  and  subsequently  measuring  their  contents.  This 
method  as  well  as  some  others,  has  been  employed  for  the  same 
purpose  by  Prof.  S.  G.  Morton  of  this  city,  in  the  preparation  of 
his  elegant  and  interesting  work  on  Crania  Americana,  and  the 
results  have  been  so  carefully  detailed  by  him,  as  to  leave  hence- 
forth little  to  be  wished  upon  a  subject  which  has  excited  much 
attention  among  physiologists.  The  whole  capacity  of  the 
cranium  is  found  on  an  average,  greater  in  the  Caucasian  variety 
of  the  human  race,  than  in  any  other. 

The  Head  of  the  Foetus. 

In  the  foetus,  those  bones,  which  form  the  vault  of  the  cra- 
nium, originally  consist  of  one  plate  only ;  which  is  compose^ 
of  radiant  fibres. 

At  birth,  the  os  frontis  consists  of  two  pieces,  which  join  each 
other  in  the  middle  of  the  forehead. 

The  parietal  bones  are  each  in  a  single  piece ;  but  they  are 
incomplete  at  their  edges  and  their  angles. 

The  temporal  bones  have  no  appearance  of  mastoid  or  styloid 
processes.  Instead  of  a  meatus  auditorius  externus,  there  is  a 
bony  ring  in  which  the  membrana  tympani  is  fixed.  The 
squamous  and  petrous  portions,  and  this  ring,  are  originally 
formed  separate ;  but  at  the  period  of  birth  they  often  adhere  to 
each  other. 

The  os  occipitis  is  composed  of  four  pieces :  the  first  and 
largest,  extends  from  the  beginning  or  angle  of  the  lambdoidal 
suture  to  the  upper  edge  of  the  great  occipital  foramen.  Each 
side  of  the  foramen,  and  the  condyle  on  it,  is  formed  by  a 
distinct  piece.  The  front  part  is  formed  by  the  cuneiforrc 


136  HEAD  OF  THE  FOETUS. 

process,  which  is  separate  from  the  other  parts  and  forms  the 
fourth  piece. 

The  sphenoidal  bone  may  be  separated  by  maceration  into 
three  pieces.  The  body  and  the  little  wings  form  one  piece. 
Each  of  the  great  wings,  with  the  pterygoid  processes  united 
to  it,  forms  also  a  piece.  The  body  of  the  bone  is  entirely 
solid. 

A  large  part  of  the  ethmoid9  is  in  a  cartilaginous  state.  It  is 
divided  into  two  portions  by  a  partition  of  cartilage,  which 
occupies  the  place  of  the  nasal  plate  and  the  crista  galli. 

In  consequence  of  the  imperfect  formation  of  the  bones  which 
compose  the  vault  of  the  cranium,  there  are  several  deficiencies 
in  it.  Thus  the  superior  anterior  angles  of  the  parietal  bones 
being  incomplete,  and  also  the  upper  angles  of  the  pieces  which 
compose  the  os  frontis,  a  vacuity  with  four  sides  is  occasioned, 
which  is  termed  the 

Anterior  fontanel.  This  opening  may  be  distinguished  by  its 
form,  as  well  as  its  greater  size,  from  another  vacuity  which  is 
produced  in  a  similar  way  at  the  other  end  of  the  sagittal  suture, 
and  called  the 

Posterior  fontanel:  but  as  there  are  only  three  bones  con- 
ce*rned  in  its  formation,  viz.  the  two  parietal  and  the  occipital, 
this  vacuity  is  triangular. 

Besides  these,  there  are  two  other  vacuities  or  fontanels  on 
each  side,  at  the  two  lower  corners  of  each  parietal  bone :  these, 
however,  are  much  less  than  those  first  described. 

The  smaller  fontanels  do  not  continue  open  long  ;  but  the 
anterior  fontanel  is  seldom  completely  closed  before  the  end  of 
the  third  year. 

It  is  very  obvious  upon  an  examination  of  the  cranium,  that 
the  centre  of  the  base  is  better  calculated  to  resist  pressure  than 
any  other  part;  as  the  cuneiform  process  of  the  occipital  bone, 
the  petrous  portion  of  the  temporal,  and  the  body  of  the  sphe- 
noidal bone,  which  compose  a  large  part  of  it,  are  very  firm  and 
substantial. 

The  face  of  the  fcetus  differs  very  essentially  from  that  of  the 
adult.  Although  the  orbits  of  the  eyes  are  very  large  when 


THE  SPINE.  137 

compared  with  the  size  of  the  head,  that  portion  of  the  face 
which  is  below  them  is  very  small,  and  has  little  depth. 

The  upper  maxillary  bones  have  no  sinuses  in  them ;  and  their 
orbitar  plates  are  not  much  elevated  above  the  cavities  for  con- 
taining the  posterior  teeth  ;  in  consequence,  the  depth  of  the 
face  is  very  small,  and  its  whole  aspect  is  affected. 

The  nose  of  the  fwtus  differs  greatly  from  that  of  the  adult 
in  respect  to  its  sinuses  ;  for  not  only  are  the  maxillary  cavities 
wanting,  but  those  of  the  frontal  and  sphenoidal  bones  also. 

The  lower  jaw  is  formed  in  two  pieces,  which  unite  at  the 
middle ;  and  hence  the  term  symphysis  is  used  in  describing 
the  chin.  The  bone  is  not  only  less  broad  in  proportion  than 
that  of  the  adult,  but  the  Angles  are  more  obtuse,  and  the  pro- 
cesses which  arise  from  them  are  more  sloping. 

The  head  of  the  foetus  is  much  larger  in  proportion  to  the 
body  than  that  of  the  adult. 

Of  the  Trunk. 
The  Trunk  consists  of  the  SPINE,  THORAX,  and  PELVIS. 

The  Spine. 

The  spine  is  the  long  pile  of  bones  extending  from  the 
condyles  of  the  occiput  to  the  end  of  the  os  coccygis.  It  some- 
what resembles  two  unequal  pyramids  joined  in  a  common  base. 
It  is  not,  however,  straight;  for  its  upper  part  being  drawn 
backwards  by  strong  muscles,  it  gradually  advances  forwards 
to  support  the  oesophagus,  vessels  of  the  head,.&c.  Then 
it  turns  backwards,  to  make  room  for  the  heart  and  lungs. 
It  is  next  bent  forwards  to  support  the  viscera  of  the  abdomen. 
It  afterwards  turns  backwards  for  the  enlargement  of  the  pelvis.  ( 
And,  lastly,  it  is  reflected  forwards,  for  sustaining  the  lowest ' 
great  intestines. 

The  spine  is  commonly  divided  into  true  and  false  vertebra  ; 
the  former  constituting  the  long  upper  pyramid,  which  has  its 
base  below ;  while  the  false  vertebrae  make  the  shorter  lower 
pyramid,  whose  base  is  above. 


138 


Fig.  32. 


THE  VERTEBRAE. 

True  Vertebra. 

The  true  vertebra  are  the  twenty-four 
upper  bones  of  the  spine,  on  which  the  seve- 
ral motions  of  the  trunk  of  our  bodies  are  per- 
formed. Their  name  is  derived  from  the 
Latin  verb  verier  e. 

Each  of  these  vertebrae  is  composed  of  its 
body  and  processes. 

The  body  is  the  thick  spongy  forepart, 
which  is  convex  before,  concave  backwards, 
horizontal  and  flat  in  most  of  them  above  and 
below.  Numerous  small  holes,  especially 
on  the  fore  and  back  part  of  their  surface, 
giving  passage  to  their  vessels,  and  allow  the 
ligaments  to  enter  their  substance.  The  edges 
of  the  body  of  each  vertebra?  are  covered, 
especially  at  the  forepart,  with  a  ring  of  bone 
firmer  and  more  solid  than  the  substance  of 
the  body  any  where  else.  These  rings  seem 
to  be  joined  to  the  vertebrae  in  the  form  of 
epiphysis.  They  are  of  great  use  in  pre- 
venting the  spongy  bodies  from  being  broken 
in  the  motions  of  the  trunk. 

Between  the  bodies  of  each  two  adjoining 
vertebrae,  a  substance  between  the  nature  of 
ligament  and  cartilage  is  interposed  ;  which 
seems  to  consist  of  concentrical  curved  fibres, 
when  it  is  cut  horizontally ;  but  when  it  is 
divided  perpendicularly,  the  fibres  appear 


*  The  vertebral  column — consisting  of  twenty-four 
true  vertebrae  ;  and  two  false,  the  sacrum  and  os  coccygisj 
each  made  up  by  the  consolidation  of  four  bones  which 
are  separate  in  the  young  subject. — It  extends  the 
whole  length  of  the  trunk. — It  may  be  divided  into  four 
regions — the  cervical  comprising  the  seven  vertebrae  from  a  to  b. — The  dorsal,  the 
twelve  vertebrae  from  b  to  c. — The  lumbar,  the  five  vertebrae  from  c  to  d. — The 
pelvic,  or  sacro-coccygeal  portion  comprising  the  false  vertebrae,  the  sacrum  and 
coccyx  from  d  to  /. — From  e  to  /.  are  the  four  small  bones  forming  the  os 
coccygis. 


THE  VERTEBRJE.  139 

oblique  and  decussating.  The  outer  part  of  these  intervertebral 
ligaments  is  the  most  solid  and  hard;  and  they  gradually 
become  softer  till  they  are  almost  in  the  form  of  a  glairy  liquor 
in  the  centre.  The  external  fibrous  part  of  each  is  capafcle  of 
being  greatly  extended,  and  of  being  compressed  into  a  smaller 
space,  while  the  middle  fluid  part  is  incompressible,  or  nearly 
so.  The  middle  point  is  therefore  a  fulcrum  or  pivot,  on  which 
the  motion  of  a  ball  and  socket  may  be  made,  with  such  a 
gradual  yielding  of  the  substance  of  the  ligament,  in  whatever 
direction  our  spines  are  moved,  as  saves  the  body  from  violent 
shocks,  and  their  dangerous  consequences.  This  ligamento- 
cartilaginous  substance  is  firmly  fixed  to  the  horizontal  surfaces 
of  the  bodies  of  the  vertebrae,  to  Connect  them ;  in  which  it  is 
assisted  by  a  strong  membranous  ligament,  which  lines  all  their 
concave  surface,  and  by  a  still  stronger  ligament  that  covers  all 
their  anterior  convex  surface. 

The  elastic  substance  seems  to  be  in  a  state  of  compression 
by  the  exterior  ligament  and  the  bones ;  for,  if  a  section  be 
made  through  a  portion  of  the  vertebrae  and  the  intervertebral 
substance,  this  substance  will  expand,  so  that  its  surface  will 
be  much  higher  than  that  of  the  vertebrae,  h  is  s_o  elastic,  and 
so  much  confined,  in  some  subjects,  that  a  sharp  knife,  if  plunged 
into  it  will  be  gradually  ejected  when  the  hand  is  with- 
drawn. 

The  bodies  of  the  vertebrae  are,  with  some  exceptions, 
smaller  and  more  solid  above,  but  more  spongy  as  they  descend. 
The  cartilages  between  them  are  thick,  and  the  surrounding 
ligaments  are  strong  in  proportion  to  the  size  of  the  vertebrae. 
By  this  disposition,  the  greatest  weight  is  supported  on  the 
broadest,  best  secured  base,  and  the  middle  of  the  body  is 
allowed  a  large  and  secure  motion. 

From  each  side  of  the  body  of  each  vertebrae,  a  bony  bridge 
or  pedicle  is  produced  backwards,  and  to  one  side ;  from  the 
posterior  end  of  which  one  slanting  process  rises,  and  another 
descends.  The  smooth,  and  generally  the  flattest  side  of  each 
of  these  four  processes  is  covered  with  a  smooth  cartilage ;  and 
the  two  lower  processes  of  each  upper  vertebrae  are  fitted  to 


140  THE  VERTEBRA. 

and  articulated  with  the  -two  upper  processes  of  the  vertebrae 
below,  having  their  articular  ligaments  fixed  into  the  rough  line 
round  their  edges.  These  processes  are  termed  the  oblique 
or  articulating.  •*" 

From  between  the  oblique  processes  of  each  side,  another  pro- 
cess extends  laterally,  which  is  called  the  transverse. 

From  the  back  part  of  the  roots  of  the  two  oblique  processes, 
and  of  the  transverse  process  of*  each  side,  a  broad  oblique  bony 
plate  called  the  lamella  is  extended  backwards :  where  these 
meet,  the  seventh  process  of  the  vertebra  takes  its  rise,  and 
stands  out  backwards.  This  being  generally  sharp-pointed  and 
narrow-edged,  it  has  therefore  been  called  spinous  process ; 
from  which  this  whole  chain  of  bones  has  got  its  name. 

Besides  the  common  ligament  which  lines  all  the  internal  sur- 
face of  the  spinous  processes  as  well  as  of  the  bodies,  particular 
ligaments  connect  the  bony  bridges  and  processes  of  the  contig- 
uous vertebrae  together. 

The  substance  of  the  processes  is  considerably  stronger  and 
firmer,  and  has  a  thicker  external  plate  than  the  bodies  of  the 
vertebrae  themselves. 

The  seven  processes  form  a  concavity  at  their  forepart,  which, 
joined  to  the  one  at  the  back  part  of  the  bodies,  make  a  great 
hole ;  and  when  the  vertebra  are  placed  upon  each  other  in 
their  natural  order,  these  holes  form  a  long  tube  for  containing 
the  spinal  marrow. 

In  the  upper  and  lower  edge  of  each  lateral  bridge  or  pedicle, 
there  is  a  notch.  These  are  so  adapted  to  each  other  in  the 
contiguous  vertebras,  as  to  form  a  round  hole  in  each  side,  be- 
tween each  two  vertebrae,  through  which  the  nerves  proceed 
from  the  spinal  marrow,  and  its  blood-vessels  pass. 

The  articulations  of  each  two  vertebrae  are  consequently 
double ;  for  their  bodies  are  joined  by  the  intervening  cartilage 
above  described ;  and  their  oblique  processes,  being  tipped 
with  cartilages,  are  connected  together  by  ligaments  so  as  to  al- 
low a  small  degree  of  motion  on  every  side.  Hence,  it  is  evident 
that  their  centre  of  motion  is  altered  in  different  positions  of 


CERVICAL  VERTEBRJE.  141 

the  trunk :  for,  when  we  bow  forwards,  the  weight  bears 
entirely  on  the  bodies  of  the  vertebrae  ;  if  we  bend  back,  the 
oblique  processes  support  it ;  if  we  recline  to  one  side,  we  rest 
upon  the  oblique  processes  of  that  side  and  part  of  the  boclies  ; 
if  we  stand  erect  all  the  bodies  and  oblique  processes  have  their 
share  in  our  support. 

The  true  vertebrce  are  divided  into  three  classes,  which  agree 
with  each  other  in  their  general  structure,  but  are  distinguished 
by  several  peculiarities. 

These  classes  are  named  Cervical,  Dorsal,  and  Lumbar. 
The  CERVICAL  are  the  seven  uppermost  vertebrae ;  which 
are  distinguished  from  the  rest  by  these  marks  :  their  bodies 
are  smaller  and  more  solid  than  any  others  ;  and  are  flattened  on 
the  front  surface.  They  are  also  flat  behind,  where  small 
processes  rise,  to  which  the  internal  ligaments  are  fixed.  The 
upper  surface  of  the  body  of  each  vertebras  is  made  hollow, 
by  a  slanting  thin  process  which  is  raised  on  each  side.  The 
lower  surface  is  also  hollowed,  but  in  a  different  manner;  for 
here  the  posterior  edge  is  raised  a  little,  and  the  anterior  one 
is  considerably  extended.  Hence,  the  cartilages  between  these 
vertebrae  are  firmly  connected,  and  their  articulations  are 
secure. 

Fig.  33.*  These  cartilages  are  thick,  especially 

at  their  forepart;  which  is  one  rea- 
son why  the  vertebrae  project  for- 
ward as  they  descend,  and  have  the 
larger  motion. 

Their  oblique  processes  more  justly 
deserve  that  name  than  those  of  any 
other   vertebrae.     They    are    situated 
slanting  ;  the  upper  ones  having  their 
smooth    and   almost   flat   surfaces    facing   obliquely   backwards 

*  A  central  cervical  vertebra,  seen  upon  its  upper  surface.  1.  The  body 
concave  in  its  middle,  and  rising  on  each  side  into  a  slanting  thin  process  or 
ridge.  2.  The  lamina  or  lamella.  3.  The  pedicle  rendered  concave  by  the 
superior  intervertebral  notch.  4.  The  bifid  spinous  process.  5.  The  bifid  or 
notched  transverse  process.  6.  The  vertebral  foramen.  7.  The  superior  oblique 
or  articular  process.  8.  The  inferior  oblique  or  articular  process. 


142  CERVICAL  VERTEBRAE. 

and  upwards ;  while  the  inferior  oblique  processes  have  these 
surfaces  facing  obliquely  forwards  and  downwards. 

The  transverse  processes  of  these  vertebrae  are  formed  in  a 
different  manner  from  those  of  any  other  bones  of  the  spine  ; 
for,  besides  the  common  transverse  process  rising  from  between 
the  oblique  processes  of  each  side,  there  is  a  second  one  that 
comes  out  from  the  side  of  the  body  of  each  vertebras ;  and 
these  two  processes,  after  leavmg  a  circular  hole  for  the  passage 
of  the  vertebral  artery  and  vein,  unite  and  form  a  groove  on 
their  upper  surface  to  protect  the  nerves  that  pass  in  it.  They 
terminate  obtusely  on  each  side,  for  the  insertion  of  the 
muscles. 

The  spinous  processes  project  backwards  almost  horizontally. 
They  are  shorter  than  those  of  any  other  vertebrae,  and  are 
forked  or  double  at  their  ends  ;  they  therefore  allow  a  more  con- 
venient insertion  to  muscles. 

The  thick  cartilages  between  the  bodies  of  these  cervical 
vertebrae,  the  obliquity  of  their  oblique  processes,  and  the 
shortness  and  horizontal  situation  of  their  spinous  processes,  all 
conspire  to  allow  them  large  motion. 

The  holes  between  the  bony  cross  bridges,  for  the  passage 
of  the  nerves  from  the  spinal  marrow,  have  their  largest  share 
formed  in  the  lowest  of  the  two  vertebrae,  to  which  they  are 
common. 

So  far  most  of  the  cervical  vertebrae  agree ;  but  they  have 
some  particular  differences,  which  require  a  separate  conside- 
ration. 

The  first,  from  its  use  in  supporting  the  head,  has  the  name 
of  atlas.  \  Contrary  to  all  the  other  vertebrae  of  the  spine,  it 
has  no  body  ;  but,  instead  of  it,  there  is  a  bony  arch.  In  the 
convex  forepart  of  this  arch  a  small  rising  appears  ;  and  on 
each  side  of  this  protuberance,  a  small  cavity  may  be  observed. 
The  upper  and  lower  parts  of  the  arch  are  rough  and  unequal, 
where  the  ligaments  that  connect  this  vertebrae  to  the  os  occi- 
pitis,  and  to  the  second  vertebra,  are  fixed.  The  back  part  of 
the  arch  is  concave,  smooth,  and  covered  with  a  cartilage,  in 
a  recent  subject,  to  receive  the  tooth-like  process  of  the  second 


CERVICAL  VERTEBRAE.  143 

vertebra.  On  each  side  of  it  a  small  rough  sinuosity  may  be 
remarked,  where  the  ligaments  going  to  the  sides  of  the  tooth- 
like  process  of  the  following  vertebra  are  fastened ;  and  on  each 
side  a  small  rough  protuberance  and  a  depression  is  observable, 
where  the  transverse  ligament,  which  secures  the  tooth-like 
process  in  the  sinuosity,  is  fixed,  and  hinders  that  process  from 
injuring  the  medulla  spinalis  in  the  flexions  of  the  head. 

The  atlas  has  as  little  spinous  process  as  body;  but,  instead 
of  it,  there  is  a  large  bony  arch,  that  the  muscles  which  pass 
over  this  vertebra  at  that  place  might  not  be  hurt  in  extending 
the  head.  On  the  posterior  and  upper  part  of  this  arch,  there 
are  two  depressions,  where  the  recti  postici  minores  muscles  take 
their  rise ;  and  at  the  lower  part  are  two  other  sinuosities,  into 
which  the  ligaments  that  connect  this  bone  to  the  following  one 
are  fixed. 

The  superior  oblique  processes,  of  the  atlas  are  large,  and 
more  horizontal  than  those  of  any  other  vertebra.  They  form 
an  oblong  concave  surface  which  has  an  internal  aspect,  and 
corresponds  exactly  with  the  articulating  surface  on  the  external 
side  of  each  condyle  of  the  os  occipitis.  Under  the  external 
edge  of  the  posterior  part  of  each  of  these  cavities  is  the  fossa, 
or  deep  open  channel,  in  which  the  vertebral  arteries  make  the 
circular  turn,  as  they  are  about  to  enter  the  great  foramen  of  the 
occipital  bone,  and  where  the  tenth  pair  of  nerves  go  out.  In 
some  subjects,  this  fossa  is  covered  with  bone.  The  inferior 
oblique  processes,  extending  from  within  outwards  and  down- 
wards, are  large,  circular,  and  slightly  concave.  So  that  this 
vertebra,  contrary  to  the  other  six,  receives  the  bones  with  which 
it  is  articulated,  both  above  and  below.  \ 

The  transverse  processes  of  this  vertebra  are  not  much  hol- 
lowed or  forked  ;  but  are  longer  and  larger  than  those  of 
any  other  vertebrae  of  the  neck,  for  the  origin  and  insertion 
of  several  muscles ;  and,  therefore,  those  muscles  which  move 
this  vertebra  on  the  second,  have  a  considerable  lever  to  act 
with,  because  of  the  distance  of  their  insertion  from  the  axis  of 
revolution. 

The  hole  for  the  medulla  spinalis  is  larger  in  the  atlas  than 


144  CERVICAL  VERTEBRA. 

in  any  other  vertebra,  not  only  on  account  of  the  medulla  being 
largest  here,  but  also  to  prevent  its  being  hurt  by  the  motions  of 
this  vertebra  on  the  second.  This  large  hole,  and  the  long 
transverse  processes,  make  this  the  brqadest  vertebra  of  the  neck. 
The  condyles  of  the  os  occipitis  move  forwards  and  backwards 
in  the  superior  oblique  processes  of  this  vertebra  ;  but  from  the 
figure  of  the  bones  forming  these  articulations,  it  is  evident  that 
very  little  motion  can  here  be"  allowed  to  either  side ;  and  there 
must  be  still  less  circular  motion. 

The  second  vertebra  of  the  neck  is  called  dentata.  It  is 
somewhat  of  a  pyramidal  figure,  being  large,  and  extended  down- 
wards, especially  in  front,  to  enter  into  a  hollow  of  the  vertebra 
below  ;  while  the  upper  part  has  a  long  process,  with  its  extre- 
mity formed  into  an  obtuse  point.  This  process,  from  its  sup- 
posed resemblance  to  a  tooth,  has  given  name  to  the  vertebra. 
The  side  of  it,  on  which  the  concave  surface  of  the  anterior  arch 
of  the  first  vertebra  plays,  is  convex,  smooth,  and  covered 
with  a  cartilage  ;  and  it  is  of  the  same  form  behind,  to  accom- 
modate the  ligament  which  is  extended  transversely  from  one 
rough  protuberance  of  the  first  vertebra  to  the  other,  and  is 
cartilaginous  in  the  middle.  A  ligament  likewise  goes  out  in 
an  oblique  transverse  direction,  from  each  side  of  the  processus 
dentatus,  to  be  fixed  at  its  other  end  to  the  first  vertebra,  and 
Fig.  34.*  to  the  occipital  bone ;  and  another  liga- 

ment rises  up  from  near  the  point  of  the 
process  to  the  os  occipitis. 

The  superior  oblique  processes  of  the 
vertebra  dentata  are  large,  circular, 
very  nearly  in  a  horizontal  position,  and 
slightly  convex,  to  be  adapted  to  the 
inferior  oblique  processes  of  the  first 


*  A  lateral  view  of  the  axis  or  vertebra  dentata.  1.  The  body.  2.  The  dentated 
or  odontoid  process.  3.  The  smooth  surface  on  the  anterior  face  of  the  tooth-like 
or  dentated  process,  which  articulates  with  the  posterior  face  of  the  anterior  arch 
of  the  atlas.  4.  The  lamina.  5.  The  spinous  process.  6.  The  transverse  pro- 
cess pierced  obliquely  by  the  foramen  for  the  vertebral  artery.  7.  The  superior 
oblique  or  articular  process.  8.  The  inferior  articular  process. 


-  CERVICAL' VERTEBRJE.     •  145 

vertebra.  The  inferior  oblique  processes  of  this  vertebra 
answer  exactly  to  the  description  given  of  those  common  to 
all  the  cervical  vertebrae. 

The  transverse  processes  of  the  vertebra  dentata  are  short, 
very  little  hollowed  at  their  upper  part,  and  not  forked  at  their 
ends ;  and  the  canals  through  which  the  vertebral  arteries  pass, 
are  reflected  outwards  about  the  middle  of  each  process,  so  that  • 
the  course  of  these  vessels  may  be  directed  towards  the  trans- 
verse processes  of  the  first  vertebra.  Had  this  curvature  of  the 
arteries  been  made  in  a  part  so  movable  as  the  neck  is,  while 
they  were  not  defended  by  a  bone  and  placed  in  the  cavity  of 
that  bone,  scarce  a  motion  could  have  been  performed  without 
the  utmost  hazard  of  compression.  This  is  the  third  instance, 
of  similar  mechanism  in  cases  of  sudden  curvature  of  arte- 
ries. The  first  is  the  passage  of  the  carotids  through  the 
temporal  bones ;  and  the  second  is  that  lately  described,  where 
the  vertebral  arteries  turn  round  the  oblique  processes  of  the 
first  vertebra,  to  come  at  the  great  hole  of  the  occipital  bone. 

The  spinous  process  of  this  vertebra  is  thick,  strong,  and 
short,  to  give  sufficient  origin  to  the  musculi  recti  majores  and 
obliqui  inferiores,  and  to  prevent  the  contusion  of  the^se  and 
other  muscles  in  pulling  the  head  back. 

The  four  cervical  vertebras  which  are  next  in  order  have 
nothing  particular  in  their  structure,  but  agree  with  the  general 
description.  The  seventh  vertebra  approaches  the  form  of  those 
of  the  back,  having  the  upper  and  lower  surfaces  less  excavated 
than  the  others.  The  oblique  processes  are  more  perpendicular ; 
and  the  spinous  as  well  as  transverse  processes  are  without 
bifurcation. 

After  an  examination  of  the  condyles  of  the  os  occipitis,  and 
of  the  whole  structure  of  the  atlas  and  vertebra  dentata,  it  will 
be  evident,  that  the  flexion  and  extension  of  the  head,  or  its 
motion  backwards  and  forwards,  is  effected  by  the  movements 
of  the  condyles  of  the  occipital  bone  on  the  atlas ;  and  that  in 
the  rotation  of  the  head,  the  atlas  revolves  to  a  certain  degree 
round  the  processus  dentatus  of  the  second  vertebra :  the  head 
necessarily  moving  with  it. 
13 


146  DORSAL    VERTEBRJE. 

The  TWELVE  DORSAL  may  be  distinguished  from  the  other 
vertebra  of  the  spine  by  the  following  marks. 

Their  bodies  are  of  a  middle  size,  between  those  of  the  neck 
and  loins.  They  are  more  convex  before  than  either  of  the 
other  two  sorts ;  and  are  flattened  laterally  by  the  pressure 
of  the  ribs,  which  are  inserted  into  small  cavities  formed  in 
their  sides.  This  flatness  of  their  sides,  which  makes  the  figure 
of  these  vertebrae  almost  a  ^ialf  oval,  is  of  great  use  ;  as  it 
affords  a  firm  articulation  to  the  ribs,  allows  the  tracheal  tube 
to  divide  at  a  small  angle,  and  the  other  large  vessels  to  run 
secure  from  the  action  of  the  vital  organs.  Their  bodies  are 
more  concave  behind  than  any  of  the  other  two  classes.  The 
upper  and  lower  surfaces  are  horizontal. 

The  cartilages  interposed  between  the  bodies  of  these  verte- 
brae are  thinner  than  in  any  other  of  the  true  vertebrae ;  and 
contribute  to  the  concavity  of  the  spine  in  the  thorax,  by  being 
thinnest  in  their  forepart. 

The  oblique  processes  are  placed  almost  perpendicularly : 
the  upper  ones  slanting  but  a  little  forwards,  and  the  lower 
ones  slanting  as  much  backwards.  The  convexity  or  concavity 
is  not  so  remarkable  as  to  require  particular  notice.  Between 
the  oblique  processes  of  opposite  sides  several  sharp  processes 
stand  out  from  the  upper  and  lower  parts  of  the  plates  which 
join  to  form  the  spinous  processes :  into  these  sharp  processes 
strong  ligaments  are  fixed  for  connecting  the  vertebrae. 

The  transverse  processes  of  the  dorsal  vertebrae  are  long, 
thicker  at  their  ends  than  in  the  middle,  and  turned  obliquely 
backwards,  which  may  be  owing  to  the  pressure  of  the  ribs ; 
the  tubercles  of  which  are  inserted  into  a  depression  near  the 
end  of  these  processes. 

The  spinous  processes  are  long,  small-pointed,  and  sloping 
downwards  and  backwards.  From  their  upper  and  back 
part  a  ridge  rises,  which  is  received  by  a  small  channel  in  the 
forepart  of  the  spinous  process  immediately  above,  which  is 
here  connected  to  it  by  a  ligament. 

The  canal  for  the  spinal  marrow  is  here  more  circular,  but 
corresponding  to  the  size  of  that  chord,  is  smaller  than  in  any 


DORSAL   VEKTEBRJE.  147 

of  the  other  vertebrae;  and   a  larger  share  of  the  holes  in   the 
Fig.  35.*  bony  bridges  for  the  transmission 

of  the  nerves,  is  formed  in  the 
vertebra  above  than  in  the  one 
below. 

The  connexion  of  the  dorsal 
vertebrae  to  the  ribs,  the  thinness 
of  their  cartilages,  the  erect  situa- 
tion of  the  oblique  processes,  the 
length,  sloping,  and  connexion  of 
the  spinous  processes,  all  contribu- 
ting to  restrain  these  vertebrae  from 

much  motion,  which  might  disturb  the  actions  of  the  heart  and 
lungs ;  and  in  consequence  of  the  little  motion  allowed  here,  the 
intervertebral  cartilages  sooner  shrivel,  by  becoming  more  solid  ; 
and  therefore  the  first  remarkable  curvature  of  the  spine 
observed,  as  people  advance  to  old  age,  is  in  the  least  stretched 
vertebrae  of  the  back ;  or  old  people  first  become  round-shoul- 
dered. 

The  bodies  of  the  four  uppermost  dorsal  vertebrae  deviate 
from  the  rule,  that  the  vertebrae  become  larger  as  they  descend  ; 
for  the  first  of  the  four  is  the  largest,  and  the  other  three  below 
gradually  become  smaller,  to  allow  the  trachea  and  large  ves- 
sels to  divide  at  smaller  angles. 

The  two  uppermost  vertebras  of  the  back,  instead  of  being 
very  prominent  forwards,  are  flattened  by  the  action  of  the 
musculi  longi  colli  and  recti  majores. 

The  proportional  size  of  the  two  little  depressions  in  the 
body  of  each  vertebra  for  receiving  the  heads  of  the  ribs  seems 
to  vary  in  the  following  manner  :  the  depression  on  the  upper 
edge  of  each  vertebra  decreases  as  far  down  as  the  fourth,  and, 
after  that,  increases. 

*  A  lateral  view  of  a  dorsal  vertebra.  1.  The  body.  2.  2.  Articular  facets 
for  the  head  of  the  ribs.  3.  The  pedicle.  4.  The  superior  intervertebral  notch. 
5.  The  inferior  intervertebral  notch.  6.  The  spinous  process.  7.  The  extremity 
of  the  transverse  process  marked  by  an  articular  surface  for  the  tubercle  of  the 
rib.  8.  The  two  superior  oblique  processes  looking  backwards.  9.  The  two 
inferior  oblique  processes  looking  forwards. 


148  LUMBAR  VERTEBRAE. 

The  transverse  processes  are  longer  in  each  lower  vertebra 
to  the  seventh  or  eighth,  with  their  smooth  surfaces,  for  the 
tubercles  of  the  ribs,  facing  gradually  more  downwards  ;  but 
afterwards,  as  they  descend,  they  become  shorter,  and  the 
smooth  surfaces  are  directed  more  upwards. 

The  spinous  processes  of  the  vertebrse  of  the  back  become 
gradually  longer  and  more  slanting  from  the  first,  as  far  down 
as  the  eighth  or  ninth  vertet5ra  ;  from  which  they  manifestly 
turn  shorter  and  more  erect. 

The  first  vertebra,  besides  an  oblong  hollow  in  its  lower 
edge  that  assists  in  forming  the  cavity  wherein  the  second  rib 
is  received,  has  the  whole  cavity  for  the  head  of  the  first  rib 
formed  in  it. 

The  eleventh  often  has  the  whole  cavity  for  the  eleventh  rib 
in  its  •  body,  and  wants  the  smooth  surface  on  each  transverse 
process. 

The  twelfth  always  receives  the  whole  head  of  the  last  rib, 
and  has  no  smooth  surface  on  its  transverse  processes,  which 
are  very  short.  The  smooth  surfaces  of  its  inferior  oblique 
processes  face  outwards  as  the  lumbar  do.  In  general  the 
upper  vertebra  of  the  back  lose  gradually  their  resemblance  to 
x  those  of  the  neck,  and  the  lower  ones  approach  gradually  to  the 
figure  of  the  lurnbar. 

Fig.  36.*  The    LUMBAR    VERTEBRA    are 

five  bones,  that  may  be  distin- 
guished from  any  others  by  these 
marks:  1.  Their  bodies,  though 
of  a  circular  form  at  their  fore- 
part, are  somewhat  oblong  from 
one  side  to  the  other.  The 
epiphysis  on  their  edges  are 
larger ;  and  therefore  the  upper  and  lower  surfaces  of  their 
bodies  are  more  concave  than  in  the  vertebrse  of  the  back. 


*  A  lateral  view  of  the  lumbar  vertebra.  1.  The  body.  2.  The  pedicle.  3. 
The  superior  intervertebral  notch.  4.  The  inferior  intervertebral  notch.  5.  The 
spinous  process.  6.  The  transverse  process.  7.  The  superior  articular  processes. 
8.  The  inferior  articular  processes. 


I 
LUMBAR  VERTEBRA.  149 

The  pedicles  are  very  strong,  the  lamella  or  laminae,  see  page 
139,  are  thick  and  narrow.  2.  The  cartilages  between  these 
vertebra  are  very  thick,  and  render  the  spine  convex  within 
the  abdomen,  by  their  great  thickness  anteriorly.  3.  The 
oblique  processes  are  strong  and  deep  ;  the  superior,  which  are 
concave,  facing  inwards,  and  the  convex  inferior  ones  facing 
outwards  ;  and  therefore  each  of  these  vertebrae  receives  the 
one  above  it,  and  it  is  received  by  the  one  below,  which  is  not 
so  evident  in  the  other  two  classes  already  described.  4.  Their 
transverse  processes  are  small,  long,  and  almost  horizontal,  for 
allowing  large  motion  to  each  bone,  and  sufficient  insertion  to 
muscles,  and  for  supporting  and  defending  the  internal  parts. 
5.  Between  the  roots  of  the  superior  oblique  and  transverse 
processes,  a  small  protuberance  may  be  observed,  where  some 
of  the  muscles  that  raise  the  trunk  of  the  body  are  inserted.  6. 
Their  spinous  processes  are  strong,  straight,  and  horizontal,  with 
broad  flat  sides,  and  a  narrow  edge  above  and  below;  this  last 
being  depressed  on  each  side,  by  muscles  ;  and,  at  the  root  of 
these  edges,  we  see  rough  surfaces  for  fixing  the  ligaments.  7. 
The  medullary  canal  is  larger  in  these  bones  than  in  the  dorsal 
vertebrae.  8.  The  holes  for  the  passage  of  the  nerves  are  more 
equally  formed  out  of  both  the  contiguous  vertebrae  than  in  the 
other  classes ;  the  upper  one  furnishes,  however,  the  larger  share 
of  each  hole. 

The  thick  cartilages  between  these  lumbar  vertebrae,  their 
deep  oblique  processes,  and  their  erect  spinous  processes,  are  all 
fit  for  allowing  large  motion,  though  it  is  not  so  great  as  what 
is  performed  in  the  neck  ;  which  appears  from  comparing  the 
arches  that  the  head  describes  when  moving  on  the  neck  or  the 
loins  only. 

The  lumbar  vertebrae,  as  they  descend,  have  their  oblique 
processes  at  a  great  distance  from  each  other,  and  facing  more 
backward  and  forwards. 

The  transverse  and  spinal  processes  of  the  first  and  last  lumbar 
vertebrae  are  shorter  than  those  in  the  middle. 

The  epiphyses  round  the  edges  of  the  bodies  of  the  lumbar 
vertebrae  are  most  raised  in  the  two  lowest;  which  conse- 


150  LUMBAR  VERTEBRJE. 

quently  make  them  appear  hollower  in  the  middle  than  the 
others  are. 

The  body  of  the  fifth  vertebrae  is  rather  thinner  "than  that  of 
the  fourth.  The  spinous  process  of  this  fifth  is  smaller,  and  the 
oblique  processes  face  more  backwards  and  forwards,  than  those 
of  any  other  lumbar  vertebrae. 

In  consequence  of  this  particular  construction,  the  spine  is 
capable  of  flexion,  principally  in  an  interior  and  lateral  direc- 
tion, and  also  of  extension.  It  ought  to  be  remarked,  that 
during  flexion  it  forms  a  curve,  and  not  an  angle ;  for,  in  the 
last  case,  the  spinal  marrow  would  be  more  or  less  com- 
pressed. 

The  cervical  vertebrae  have  most  motion,  and  the  dorsal  the 
least.  This  circumstance  is  fully  explained  by  the  form  of  the 
different  parts  of  these  vertebrae,  and  the  difference  in  the  thick- 
ness of  the  intervertebral  substance.  The  necessity  of  fixing 
the  dorsal  vertebrae  is  very  evident:  as  their  motion  would 
greatly  interfere  with  the  motion  of  the  ribs  in  respiration. 

The  lumbar  vertebrae  have  more  motion  than  is  commonly 
supposed  ;  for,  in  addition  to  a  certain  degree  of  flexion,  they 
perform  a  species  of  rotation  or  twisting,  which  is  very  observa- 
ble in  persons  who  are  diseased  in  one  of  their  hip  joints  ;  such 
persons  move  their  whole  pelvis,  by  a  rotation  of  the  lumbar 
vertebrae,  to  avoid  moving  the  diseased  joint. 
— The  first  cause,  the  predisposing  cause  of  spinal  curvatures 
is  the  relative  feebleness  of  the  spinal  column,  compared  to  the 
forces  exercised  upon  it,  at  the  same  time  that  the  bones,  by  a 
premature  increase,  or  by  a  lesion  of  nutrition  as  yet  little 
known,  do  not  acquire  the  degree  of  solidity  necessary  to  resist 
the  action  of  the  muscles,  and  especially  the  weight  of  the  vis- 
cera contained  in  the  head  and  chest.  There  results  from  this 
necessarily  a  curvature  in  some  direction  at  one  of  the  points  of 
the  lever. 

— The  direction  of  the  curvature  will  be  determined  by  the 
inequality  of  the  forces  brought  into  play  around  it.  For  with- 
out this  inequality,  the  curvature  would  be  direct ;  that 
is,  straight.  It  has  place  ordinarily  to  the  left,  because 


FALSE  VERTEBRA.  151 

the  muscles  of  the  right  side,  stronger  than   those  of  the  left, 
draw  the  vertebra  in  that  direction,  as  Ludvvig  first  pointed  out. — 


False  Vertebra. 

The  lower  pyramid  or  under  part  of  the  spine,  consists  of  one 
large  triangular  bone,  called  the  os  sacrum,  and  of  some  small 
bones,  denominated  the  os  coccygis. 

These  bones  are  called  the  false  vertebrae,  because  the  sacrum 
in  young  subjects  is  composed  of  five  distinct  bones,  each  of 
which  has  some  resemblance  to  a  vertebra  ;  but  they  are  com- 
pletely united  in  the  adult,  and  form  but  one  bone,  which  is 
supposed  to  have  been  denominated  sacrum,  because  it  was 
offered  in  sacrifice  by  the  ancients. 

The  os  sacrum  is  of  a  triangular  form,  with  its  base  upwards. 
It  is  concave  anteriorly,  and  convex  posteriorly.     The  middle 
of  the  bone,  when  viewed  anteriorly,  appears  to  be  composed  of 
the  bodies  of  five  vertebrae,  united  to  each  other,  and  their  union 
is  marked  by  four  transverse  lines.     At  the   two  extremities  of; 
each  of  these  lines,  are  large  round  holes,  which  communicate \ 
with  the  vertebral  cavity  of  the  bone. 

On  the  exterior  sides  of  these  holes  the  surface  is  free  from 
any  marks  of  the  original  separation. 

The  middle  of  the  upper  surface,  or  base  of  the  bone,  is 
formed  for  articulating  with  the  last  lumbar  vertebra,  and  has 
two  oblique  t- processes,  with  a  groove  in  each  side,  which  forms 
part  of  the  foramen  for  transmitting  the  twenty-fourth  pair  of 
nerves. 

The  back  part  of  the  os  sacrum  is  rough  and  convex  ;  in  the 
middle  there  are  commonly  three  processes  similar  to  the  spinous 
processes  of  the  lumbar  vertebrae,  and  a  fourth,  which  is  much 
smaller.  Below  this,  there  is  a  deficiency  of  the  bony  spine, 
and  the  vertebral  cavity  is  consequently  open  behind,  but  the 
sides  of  the  canal  continue  lower  down. 

On  each  side  of  the  spinous  processes  are  four  smaller  holes, 
which  are  opposite  to  the  larger  holes  on  the  anterior  surface. 
Between  the  spinous  processes  and  the  anterior  part,  which 


, 


152  OS    COCCYGIS. 

Fig.  37.*  resembles   the  bodies  of  vertebrae,  is 

the  continuation  of  the  vertebral 
cavity  which  contains  the  spinal 
marrow.  From  the  cauda  equina, 
contained  in  this  cavity,  the  great 
nerves  of  the  lower  extremities  pass 
off}  through  the  large  holes  on  the 
antwior  surface,  and  some  small 
nerves  through  the  posterior  holes. 

In  some  bones  the  spinous  pro- 
cesses are"  entirely  deficient,  and 
the  cavity  above  mentioned  is  completely  open  behind  ;  but  the 
contained  parts  are  defended  by  strong  membranes. 

The  anterior  part  of  each  lateral  surface  is  covered  by  a 
plate  of  cartilage,  and  articulated  to  the  os  ilium.  The  poste- 
rior part  is  rough,  and  perforated  by  the  fibres  of  the  strong 
ligaments,  which  are  inserted  into  it. 

On  the  posterior  surface  of  the  sacrum,  the  sides  of  the  open 
part  of  the  vertebral  canal  terminate,  so  as  to  form  a  notch 
through  which  passes  the  twenty-ninth  pair  of  nerves. 

The  os  sacrum  is  very  spongy,  and  is  lighter  in  proportion  to 
its  bulk  than  any  bone  in  the  body:  it  is  defended  by  the 
muscles  that  cover  it,  and  the  ligaments  which  adhere  to  it.  It 
is  articulated,  above,  to  the  last  lumbar  vertebrae  ;  below,  to  the 
os  coccygis  by  its  apex  and  two  cornua ;  and  on  the  sides,  to 
the  ossa  ilia. 

That  triangular  chain  of  bones  depending  from  the  os 
sacrum,  in  which  each  bone  becomes  smaller  as  it  descends, 
till  the  last  ends  in  a  small  tubercle,  is  called  os  coccygis.  It 
is  convex  behind,  and  concave  before  ;  from  which  crooked 


*  The  sacrum  seen  upon  its  anterior  surface.  1,  1.  The  transverse  lines 
marking  the  original  constitution  of  the  bone  of  four  pieces.  2,  2.  The  anterior 
sacral  foramina.  3.  The  promontory  of  the  sacrum.  4.  The  ear-shaped  surface 
which  articulates  with  the  ilium.  5.  The  sharp  edge  to  whjch  the  sacro-ischiatic 
ligaments  are  attached.  6.  The  vertebral 'articular  surface.  7.  The  broad  tri- 
angular surface  which  supports  the  psoas  muscle  and  lumbosacral  nerve.  8. 
The  articular  process  of  the  right  side.  9.  The  inferior  extremity,  or  apex  of 
the  sacrum.  10.  One  of  the  sacral  cornua.  11.  The  notch  which  is  converted 
into  a  foramen  by  the  coccyx. 


OS  COCCYGIS.  153 

pyramidal  figure,  which  was  thought  to  resemble  a  cuckoo's 
beak,  the  name  is  derived. 

There  are  four  pieces  in  people  of  middle  age.  In  children, 
they  are  almost  wholly  cartilaginous.  In  old  subjects,  all  the 
bones  are  united,  and  become  frequently  one  continued  bone 
with  the  os  sacrum. 

The  highest  of  the  four  bones  is  the  largest,  with  shoulders 
extended  farther  to  each  side  than  the  end  of  the  os  sacrum  ; 
which  enlargement  may  serve  as  a  distinguishing  mark  to  fix 
the  limits  of  either  bone.  The  upper  surface  of  this  bone  is  a 
little  hollow.  From  the  back  of  that  bulbous  part  called  its 
shoulders,  a  process  often  rises  up  on  each  side,  to  join  with 
the  os  sacrum.  Sometimes  these  shoulders  are  joined  to  the 
sides  of  the  open  end  of  the  vertebral  canal,  to  form  the  hole 
in  each  side  common  to  these  two  bones,  for  the  passage  of  the 
twenty-ninth  pair  of  spinal  nerves.  Immediately  below  the 
shoulders  of  the  os  coccygis,  a  notch  may  be  remarked  on  each 
side,  where  the  thirtieth  pair  of  the  spinal  nerves  passes.  The 
lower  end  of  this  bone  is  formed  into  a  small  head,  which  very 
often  is  hollow  in  the  middle. 

The  three  lower  bones  gradually  become  smaller,  and  are 
spongy,,  but  are  strengthened  by  a  strong  ligament,  which 
covers  and  connects  them.  Their  ends,  by  which  they  are 
articulated,  are  formed  in  the  same  manner  as  those  of  the  first 
bone. 

Between  each  of  these  four  bones  of  young  subjects  a  carti- 
lage is  interposed ;  therefore  their  articulation  is  analogous  to 
that  of  the  bodies  of  the  vertebrae  of  the  neck ;  for  the  lower 
end  of  the  os  sacrum,  and  of  each  of  the  three  superior  bones 
of  the  os  coccygis,  has  a  small  depression  in  the  middle ;  and 
the  upper  part  of  all  the  bones  of  the  os  coccygis,  is  a  little 
concave,  and,  consequently,  the  interposed  cartilages  are  thick- 
est in  the  middle,  to  fill  up  both  cavities ;  by  which  they 
connect  the  bones  more  firmly.  When  the  cartilages  ossify, 
the  upper  end  of. each  bone  is  formed  into  a  cavity,  exactly 
adapted  to  the  protuberant  lower  end  of  the  bone  immediately 
above.  From  this  sort  of  articulation,  it  is  evident  that,  unless 


154  VERTEBRAL  CAVITY. 

when  these  bones  grow  together,  all  of  them  are  capable  of 
motion ;  of  which  the  first  and  second  enjoy  the  largest  share. 

The  lower  end  of  the  fourth  bone  terminates  in  a  rough  point, 
to  which  a  cartilage  is  appended. 

To  the  sides  of  these  bones  of  the  os  coccygis,  the  coccygaei 
muscles,  and  part  of  the  levatores  ani,  and  of  the  glutaei  maximi, 
are  fixed. 

The  connexions  of  thes%  bones  hinder  them  from  being 
moved  to  either  side ;  and  their  motion  backwards  and  for- 
wards is  much  confined  :  yet,  as  their  ligaments  can  be  stretched 
by  a  considerable  force,  it  is  of  great  advantage  in  the  excretion 
of  the  faeces  alvinae,  and  much  more  in  child-bearing,  that  these 
bones  should  remain  movable ;  and  the  right  management  of 
them,  in  delivering  women,  is  very  important.  The  mobility 
of  the  os  coccygis  diminishing  as  people  advance  in  age, 
especially  when  its  ligaments  and  cartilages  have  not  been 
kept  flexible  by  being  stretched,  is,  probably,  one  reason  why 
women,  who  are  advanced  in  years  before  they  marry,  have  gen- 
erally difficult  parturition. 

These  bones  serve  to  sustain  the  intestinum  rectum ;  and, 
therefore,  are  curved  forwards ;  by  which  they  are  preserved, 
as  well  as  the  muscles  and  teguments,  from  any  injury  when 
sitting  with  the  body  inclined  back. 

The  Vertebral  Cavity  for  containing  the  Spinal  Marrow. 

The  canal,  formed  by  the  foramina  of  the  different  vertebrae, 
when  these  bones  are  placed  in  their  natural  order,  extends 
from  the  great  occipital  foramen  to  the  end  of  the  sacrum.  Its 
direction  varies  with  the  different  curvatures  of  the  spine,  and 
its  figure  and  diameter  are  also  very  different  in  different 
places. 

In  the  cervical  vertebrae,  it  is  largest,  and  nearly  triangular 
in  form ;  in  the  dorsal,  it  is  much  smaller  and  almost  cylin- 
drical ;  in  the  lumbar,  it  is  somewhat  enlarged,  and  approaches 
again  to  the  triangular  figure  ;  in  the  sacrum,  it  is  broad,  but  flat, 
and  diminishes  gradually,  so  as  to  assume  the  form  of  a  long 
triangle. 


THE    RIBS.  155 

It  has  a  ligamentous  lining,  which  will  be  described,  when  an 
account  is  given  of  the  fresh  bones  and  their  ligaments. 

The  Thorax. 

The  thorax  resembles  a  flattened  cone,  cut  away  obliquely  at 
its  basis  ;  and  regularly  truncated  at  its  apex. 

It  is  formed  by  the  dorsal  vertebrae  behind,  the  ribs  on  the 
sides,  and  the  sternum  before. 

The  Ribs 

Are  long  crooked  bones,  placed  in  an  oblique  direction 
downwards  as  respects  the  back-bone. -  Their  number  is  gene- 
rally twelve  on  each  side ;  though  sometimes  eleven  or  thirteen 
have  been  found. 

They  are  convex  externally,  and  concave  internally.  They 
are  made  smooth  by  the  action  of  the  contained  parts,  which,  on 
this  account,  are  in  no  danger  of  being  hurt  by  them. 

The  ribs  approach  towards  a  round  form  at  their  extremities, 
near  the  vertebrae.  Farther  forwards  they  are  flat  and  broad, 
and  have  an  upper  and  lower  edge  ;  each  of  which  is  made 
rough  by  the  action  of  the  intercostal  muscles  inserted  into 
them.  These  muscles  being  all  of  nearly  equal  force,  and 
equally  stretched  in  the  interstices  of  the  ribs,  prevent  the 
broken  ends  of  these  bones,  in  a  fracture,  from  being  removed 
far  out  of  their  natural  place,  to  interrupt  the  motion  of  the  vital 
organs.  The  upper  edge  of  the  ribs  is  more  obtuse,  and 
rounder  than  the  lower,  which  is  deepened  on  its  internal  side 
by  a  long  fossa,  for  lodging  the  intercostal  vessels  and  nerves : 
on  each  side  of  which  there  is  a  ridge,  to  which  the  intercostal 
muscles  are  fixed.  The  fossa  is  not  observable  at  the  ends  of 
the  ribs ;  for,  at  the  posterior,  or  root,  the  vessels  have  not  yet 
reached  the  bones ;  and,  at  .the  fore  end,  they  are  split  away 
into  branches,  to  serve  the  parts  between  the  ribs. 

From  this  situation  of  the  blood-vessels,  has  originated  the 
rule  adopted  by  surgeons,  that  the  incision,  in  cases  of  empyema, 
&c.,  should  be  made  midway  between  the  spine  and  sternum, 
and  that  the  lower  edge  of  the  upper  rib  should  be  avoided. 

*  '  •  ~      ^ 

/?' 

^/ 


156 


THE     RIBS. 


Fig.  38.*  At  the  posterior  end  of 

each  rib,  a  little  head  is 
formed,  which  is  divided 
by  a  middle  ridge  into  two 
flat  or  hollow  surfaces  ; 
the  lowest  of  which  is  ge- 
nerally the  broadest  and 
deepest.  The  two  surfaces 
are  joined  to  the  bodies  of 
two  different  vertebrae, 
and  the  ridge  forces  itself 
into  the  intervening  carti- 
lages. A  little  way  from 
this  head,  we  find,  on  the 
external  surface,  a  small 
cavity,  where  mucilagi- 
nous glands  are  lodged ; 
and  round  the  head,  the  bone  appears  spongy,  where  the 
capsular  ligament  of  the  articulation  is  fixed.  Immediately 
beyond  this,  a  flattened  tubercle  rises,  with  a  small  cavity  at 
its  root,  which  is  surrounded  by  a  roughness,  for  the  articula- 
tion of  the  rib  with  the  transverse  process  of  the  lowest  of  the 
two  vertebrae,  with  which  the  head  of  the  rib  is  joined. 
Advancing  farther  on  this  external  surface,  another  smaller 
tubercle  may  be  observed  in  most  cases,  into  which  ligaments 
connecting  the  ribs  to  each  other,  and  to  the  transverse  pro- 
cesses of  the  vertebrae  and  portions  of  the  longissimus  dorsi, 
are  inserted.  Beyond  this,  these  bones  are  made  flat  by  the 
sacro-lumbalis  muscle,  which  is  inserted  into  the  part  of  this 
flat  surface  farthest  from  the  spine,  where  each  rib  makes  a 
considerable  curve,  called  by  some  its  angle.  Then  the  rib 

*  An  anterior  view  of  the  thorax.  J .  The  superior  piece  of  the  sternum.  2. 
The  middle  piece.  3.  The  inferior  piece,  or  ensiform  cartilage.  4.  The  first 
dorsal  vertebra.  5.  The  last  dorsal  vertebra.  6.  The  first  rib.  7.  Its  head. 

8.  Its  neck,  resting  against  the  transverse  process  of  the  first  dorsal  vertebra. 

9.  Its  tuberosity.     10.  The  seventh  or  last  true  rib.     11.  The  costal  cartilages  of 
the  true  ribs.     12.  The  two  last  false  ribs — the  floating  ribs.     13.  The  groove 
along  the  lower  border  of  the  rib  for  the  lodgment  of  the  intercostal  vessels  and 
nerve. 


THE     RIBS.  157 

begins  to  turn  broad,  and  continues  so  to  its  anterior  end,  which 
is  hollow  and  spongy,  for  the  reception  of,  and  firm  coalition 
with,  the  cartilage  that  runs  thence  to  be  inserted  into  the^ter- 
num,  or  to  be  joined  with  some  other  cartilage.  In  adults,  the 
cavity  at  this  end  of  the  ribs  is  generally  smooth. 

The  substance  of  the  ribs  is  spongy,  cellular,  and  only  covered 
with  a  very  thin  external  lamellated  surface,  which  increases  in 
thickness  and  strength  as  it  approaches  the  vertebrae. 

To  the  fore  end  of  each  rib  a  long,  broad,  and  strong  cartilage 
is  fixed,  which  reaches  the  sternum,  or  is  joined  to  the  cartilage 
of  the  next  rib.  This  course,  however,  is  not  in  a  straight  line 
with  the  rib  :  for  the  cartilages  generally  make  a  considerable 
flexure,  the  concave  part  of  which  is  upwards;  therefore,  at 
their  insertion  into  the  sternum,  they  make  an  obtuse  angle 
above,  and  an  acute  one  below.  These  cartilages  are  of  such  a 
length  as  never  to  allow  the  ribs  to  come  to  a  right  angle  with 
the  spine ;  but  they  keep  them  situated  so  obliquely  as  to  make 
the  angle  very  considerably  obtuse  above,  till  a  force  exceeding 
the  elasticity  of  the  cartilage  is  applied.  These  cartilages,  as 
all  others,  are  firmer  and  harder  internally  than  they  are  on 
their  external  surface  ;  and,  sometimes,  in  old  people,  all  their 
middle  substance  becomes  bony,  while  a  thin  cartilaginous 
lamella  appears  externally.  The  ossification,  however,  begins 
frequently  at  the  external  surface.  The  greatest  alternate 
motions  of  the  cartilages  being  made  at  their  great  curvature, 
that  part  remains  frequently  cartilaginous  after  all  the  rest  is 
ossified. 

The  ribs  then  are  articulated  at  each  end,  and  that  behind 
is  doubly  joined  to  the  vertebrae ;  for  the  head  is  received  into 
the  cavities  of  two  bodies  of  the  vertebra?,  and  a  larger  tubercle 
is  received  into  the  depression  in  the  transverse  process  of  the 
lower  vertebrae.  When  we  examine  the  double  articulation,  we 
must  immediately  see,  that  no  other  motion  can  here  be  allowed 
than  upwards  and  downwards.  Since  the  transverse  process 
hinders  the  ribs  to  be  thrusted  back,  the  resistance  of  the  sternum 
on  the  other  side  prevents  the  ribs  coming  forward ;  and  each 
of  the  two  joints,  with  the  other  parts  attached,  oppose  its 
14 


158  THE    RIBS. 

turning  round.  But  then  it  is  likewise  as  evident,  that  even 
the  motion  upwards  and  downwards  can  be  but  small  in  any 
one  rib  at  the  articulation  itself.  But  as  the  ribs  advance 
forwards,  the  distance  from  their  centre  of  motion  increasing, 
the  motion  must  be  larger ;  and  it  would  be  very  conspicuous 
at  their  anterior  ends,  were  they  not  resisted  there  by  the  car- 
tilages which  yield  so  little,  that  the  principal  motion  is  per- 
formed by  the  middle  part  of  the  ribs,  which  turns  outwards 
and  upwards,  and  occasions  the  twist  remarkable  in  the  long 
ribs  at  the  place  near  their  fore  end  where  they  are  more 
resisted. 

The  ribs  differ  from  each  other  in  the  following  respects : 
The  upper  rib  is  the  most  crooked  ;  and  as  they  descend 
they  become  straighter.  Their  obliquity,  with  respect  to  the 
spine,  increases  as  they  descend,  so  that  though  their  distances 
from  each  other  are  nearly  equal  at  their  back  part,  yet  at  their 
fore  ends  the  distances  between  the  lower  ribs  must  increase. 
In  consequence  of  this  increased  obliquity  of  the  lower  ribs, 
each  of  their  cartilages  makes  a  greater  curve  in  its  progress 
from  the  rib  towards  the  sternum  ;  and  the  tubercles  that  are 
articulated  to  the  transverse  processes  of  the  vertebrae,  have 
their  smooth  surfaces  gradually  facing  more  upwards.  The 
ribs  becoming  thus  more  oblique,  while  the  sternum  advances 
forwards  in  its  descent,  makes  the  distance  between  the  sternum 
and  the  anterior  end  of  the  lower  ribs  greater  than  between  the 
sternum  and  the  ribs  above ;  consequently,  the  cartilages 
of  those  ribs  that  are  joined  to  the  breast  bone  are  longer  in  the 
lower  than  in  the  higher  ones.  These  cartilages  are  placed 
nearer  to  each  other  as  the  ribs  descend,  which  occasions  their 
curvature  to  be  greater. 

The  length  of  their  ribs  increases  fromthe  first  and  upper- 
most rib,  as  far  down  as  the  seventh  ;  and  from  that  to  the 
twelfth,  it  gradually  diminishes.  The  superior  of  the  two 
surfaces,  by  which  the  ribs  are  articulated  to  the  bodies  of  the 
vertebras,  gradually  increases  from  the  first  to  the  fourth  rib, 
and  is  diminished  after  that  in  each  lower  rib.  The  distance 
of  their  angles  from  the  heads  always  increases  as  they 


THE     RIBS.  159 

descend  to  the  ninth,  because  of  the  greater  breadth  of  the  sacro- 
lumbalis  muscle. 

The  ribs  are  commonly  divided  into  true  and  false. 

The  true  ribs  are  the  seven  uppermost  of  each  side.  Their 
cartilages  are  all  gradually  longer  as  they  descend,  and  are  joined 
to  the  breast  bone  :  so  that,  being  pressed  constantly  between 
two  bones,  they  are  flattened  at  both  ends ;  and  are  thicker, 
harder,  and  more  liable  to  ossify  than  the  other  cartilages  that 
are  not  subject  to  so  much  pressure.  These  bones  include  the 
heart  and  lungs  ;  and  therefore  are  called  true  ribs. 

The  five  inferior  ribs  of  each  side  are  the  false,  whose  carti- 
lages do  not  reach  to  the  sternum  ;  but  on  this  account  having 
less  pressure,  their  substance  is  softer.  To  these  five  ribs  the 
circular  edge  of  the  diaphragm  is  connected. 

The  first  rib  of  each  side  is  so  situated,  that  the  flat  sides  are 
above  and  below,  while  one  edge  is  placed  inwards,  and  the 
other  outwards,  or  nearly  so  ;  therefore  sufficient  space  is  left 
above  it  for  the  subclavian  vessels  and  the  muscles ;  and  the 
broad  concave  surface  is  opposed  to  the  lungs.  But  in  conse- 
quence of  this  situation,  the  channel  for  the  intercostal  vessels  is 
not  to  be  found.  The  head  of  this  rib  is  not  divided  into  two 
plane  surfaces  by  a  middle  ridge,  because  it  is  only  articulated 
with  the  first  vertebra  of  the  thorax.  Its  cartilage  is  frequently 
ossified  in  adults,  and  is  united  to  the  sternum  at  right  angles. 
This  first  rib  frequently  has  a  ridge  rising  near  the  middle  of  its 
posterior  edge,  where  one  of  the  heads  of  the  scalenii  muscles 
rises.  Farther  forward  it  is  flattened,  or  sometimes  depressed 
by  the  clavicle. 

The  position  of  the  second  rib  is  such  that  its  two  broad 
surfaces  have  oblique  aspects,  inward  and  downwards,  outwards, 
and  upwards,  so  as  to  make  the  surface  of  the  thorax  uniform  : 
and  it  may  be  observed  of  all  the  ribs,  that  the  aspect  of  their 
surfaces  is  varied  upon  this  principle,  according  to  their  situation 
in  the  thorax. 

The  sixth,  seventh,  and  eighth  ribs  have  their  cartilages 
nearly  contiguous.  They  are  frequently  joined  to  each  other 
by  cross  cartilages  ;  and  frequently  the  cartilages  of  the  eighth, 


160  THE    STERNUM. 

ninth,  and  tenth,  are  connected  to  the  former,  and  to  each  other 
by  firm  ligaments. 

The  eleventh,  and  sometimes  the  tenth  rib,  has  no  tubercle 
for  its  articulation  with  the  transverse  process  of  the  vertebra, 
to  which  it  is  only  loosely  fixed  by  ligaments.  The  fossa,  in  its 
lower  edge,  is  not  so  deep  as  in  the  upper  ribs  ;  because  the 
vessels  run  more  towards  the  interstice  between  the  ribs.  Its 
front  end  is  smaller  than  its  Ibody  ;  and  its  short  small  cartilage 
is  but  loosely  connected  to  the  cartilage  of  the  rib  above. 

The  twelfth  rib  is  the  shortest  and  straightest.  Its  head  is 
only  articulated  with  the  last  vertebra  of  the  thorax  ;  and 
therefore  is  not  divided  into  two  surfaces.  This  rib  is  not 
joined  to  the  transverse  process  of  the  vertebra,  and  therefore 
has  no  tubercle,  being  often  pulled  necessarily  inwards  by  the 
diaphragm,  which  an  articulation  with  the  transverse  process 
would  not  have  allowed.  The  fossa  is  not  found  at  its  upper 
edge,  because  the  vessels  run  below  it.  The  forepart  of  this 
rib  is  smaller  than  its  middle,  and  has  only  a  very  small  pointed 
cartilage  fixed  to  it.  To  its  whole  internal  side  the  diaphragm 
is  connected. 

The  Sternum 

Is  the  broad  flat  bone,  in  the  front  part  of  the  thorax.  In 
adults  it  is  composed  of  three  pieces,  which  easily  separate 
after  the  cartilages  connecting  them  are  destroyed.  .  The  two 
lower  pieces  are  frequently  found  intimately  united  ;  and  very 
often,  in  old  people,  the  sternum  is  a  continued  bony  substance 
from  one  end  to  the  other  ;  though  we  still  observe  two,  some- 
times three,  transverse  lines  on  its  surface  ;  which  are  marks  of 
the  former  divisions. 

The  sternum,  considered  as  one  bone,  is  broadest  and  thickest 
above,  and  smaller  as  it  descends.  The  internal  surface  of  this 
bone  is  somewhat  concave  for  enlarging  the  thorax :  but  the 
convexity  on  the  external  surface  is  not  so  conspicuous,  because 
the  sides  are  pressed  outwards  by  the  true  ribs  ;  the  round 
heads  of  whose  cartilages  are  received  into  seven  smooth  pits, 
formed  in  each  side  of  the  sternum,  and  are  kept  firm  there  by 


THE    STERNUM.  161 

strong  ligaments,  which,  on  the  external  surface,  have  a  par- 
ticular radiated  texture.  The  pits,  at  the  upper  part  of  the 
sternum,  are  at  the  greatest  distance  one  from  another,  and 
as  they  descend,  are  nearer ;  so  that  the  two  lowest  are  con- 
tiguous. 

The  substance  of  the  breast  bone  is  cellular,  with  a  very  thin 
external  plate,  especially  on  its  internal  surface,  where  we  may 
frequently  observe  a  cartilaginous  crust  spread  over  it.  On 
both  surfaces,  however,  a  strong  ligamentous  membrane  is 
closely  braced ;  and  the  cells  of  this  bone  are  so  small,  that  a 
considerable  quantity  of  osseous  fibres  must  be  employed  in 
the  composition  of  it.  Whence,  with  the  defence  which  the 
muscles  give  it,  and  the  movable  support  it  has  from  the 
cartilages,  it  is  sufficiently  secured  from  being  broken  :  for  it  is 
strong  by  its  quantity  of  bone ;  its  parts  are  kept  together  by 
ligaments ;  and  it  yields  enough  to  elude  considerably  any 
violence  offered. 

The  three  pieces  which  compose  this  bone  are  very  different 
from  each  other. 

The  first  piece  resembles  a  triangle,  with  the  corners  cut  off. 
The  upper  edge  of  it  is  thick,  and  has  a  regular  depression  in 
the  middle,  to  accommodate  the  trachea.  On  each  side  of  this 
depression  is  a  superficial  cavity,  which,  on  viewing  it  trans- 
versely, from  before  backwards,  appears  a  little  convex.  Into 
these  cavities  the  ends  of  the  clavicles  are  received.  Imme- 
diately below  them,  the  sides  of  this  bone  become  thinner ;  and 
in  each  a  superficial  cavity,  or  a  rough  surface  is  to  be  seen, 
where  the  first  ribs  are  received  or  joined  to  the  sternum.  In 
the  side  of  the  under  end  of  this  first  bone,  the  half  of  the  pit 
for  the  second  rib  on  each  side  is  formed.  The  upper  part  of 
the  surface  behind  is  covered  with  a  strong  ligament,  which 
secures  the  clavicles ;  and  is  afterwards  to  be  more  particularly 
taken  notice  of. 

The  second,  or  middle  division  of  this  bone,  is  much  longer, 
narrower,  and  thinner,  than   the  first;  but,  excepting  that  it  is 
a  little   narrower  above  than  below,  it   is  nearly  uniform  in  its 
14* 


162  THE    STERNUM. 

dimensions  of  breadth  or  thickness.  In  the  sides  of  it  are  com- 
plete pits  for  the  third,  fourth,  fifth,  and  sixth  ribs,  and  one 
half  of  the  pits  for  the  second  and  seventh  ;  the  lines,  which 
are  marks  of  the  former  division  of  this  bone,  being  extended 
from  the  middle  of  the  pits  of  one  side,  to  the  middle  of  the 
corresponding  pits  of  the  other  side.  Near  its  middle  an  un- 
ossified  part  of  the  bone  has  sometimes  been  found  ;  which, 
freed  of  the  ligamentous  membrane  or  cartilage  that  fills  it,  is 
described  as  a  hole.  When  the  cartilage  between  this  and  the 
first  bone  is  not  ossified,  a  manifest  motion  of  this  upon  the 
first  may  be  observed  in  respiration  ;  or  in  raising  the  sternum, 
by  pulling  the  ribs  upwards ;  or  distending  the  lungs  with  air, 
in  a  recent  subject. 

The  third  bone  is  much  less  than  the  other  two,  and  has 
only  one  half  of  the  pit  for  the  seventh  rib  formed  in  it ;  where- 
fore it  might  be  reckoned  only  an  appendix  of  the  sternum. 
In  young  subjects  it  is  always  cartilaginous,  and  is  better  known 
by  the  name  of  cartilago-xiphoides  or  ensiformis,  than  any 
other.  This  third  bone  is  seldom  of  the  same  figure,  mag- 
nitude, or  situation,  in  any  two  subjects  ;  for,  sometimes,  it  is 
triangular ;  with  one  of  the  angles  below,  and  perpendicular  to 
the  middle  of  the  upper  side,  by  which  it  is  connected  to 
the  second  bone.  In  other  persons,  the  point  is  turned  to 
one  side  ;  or  obliquely  forwards  or  backwards.  Frequently  it 
is  nearly  of  an  equal  breadth,  and  often  it  is  bifurcated  ;  some- 
times, also,  it  is  unossified  in  the  middle.  In  the  greatest  number 
of  adults,  it  is  ossified,  and  tipped  with  a  cartilage ;  in  some, 
one  half  of  it  is  cartilaginous ;  and  in  others,  it  is  all  in  a  car- 
tilaginous state. 

The  sternum  is  joined  by  cartilages  to  the  seven  upper  ribs, 
except  when  the  first  coalesce  with  it.  It  is  also  articulated 
with  the  clavicles. 

It  contributes  to  the  formation  of  the  cavity  of  the  thorax, 
and  supports  the  mediastinum.  As  a  movable  fulcrum  for  the 
ribs,  it  assists  in  respiration  ;  and  it  affords  origin  and  insertion 
to  several  muscles. 


THE     PELVIS.  163 

The  movement  of  the  Ribs  and  Sternum  in  respiration. 

The  ribs  and  their  cartilages  are  articulated  to  the  spine 
behind,  and  the  sternum  before,  in  a  way  which  admits  of  a 
compound  motion. 

They  are  drawn  from  a  position  which  slopes  obliquely 
downwards  and  forwards,  into  one  which  is  more  horizontal ; 
and  the  posterior  extremity  of  each  rib,  which  is  the  centre  of 
this  motion,  is  moved  very  little,  while  the  anterior  extremity 
moves  much  more. 

At  the  same  time,  the  ribs  perform  a  rotation  outwards, 
upon  their  extremities  connected  with  the  spine  and  sternum  ; 
in  consequence  of  which,  the  middle  of  each  rib  is  moved  out- 
wards to  a  considerable  extent. 

It  is  very  obvious,  that,  by  these  motions,  the  thorax  must  be 
enlarged  from  side  to  side,  and  from  behind  forwards. 

As  the  ribs  are  raised  from  the  oblique  towards  the  horizontal 
position,  the  sternum  is  necessarily  moved  forward  by  them; 
and,  if  this  bone  does  not  move  upon  the  first  rib,  the  rib  must 
move  to  accommodate  it :  a  small  motion  at  the  articulation  of 
the  rib  with  the  spine,  being  sufficient  to  produce  considerable 
motion  at  the  lower  end  of  the  sternum.  The  sternum,  there- 
fore, vibrates  forward  when  the  ribs  are  elevated,  and  backward 
when  they  are  depressed. 

In  easy  respiration,  these  motions  are  not  very  great,  for  then 
the  enlargement  of  the  thorax  appears  to  be  produced  by  the 
increase  of  its  vertical  diameter,  in  consequence  of  the  descent 
of  the  diaphragm ;  but  when  the  inspirations  are  very  large, 
and  when  the  descent  of  the  diaphragm  is  impeded,  as  in 
pregnancy,  and  in  a^cites,  these  motions  are  very  considerable. 

It  ought  to  be  observed,  that  the  first  rib  has  very  little  motion, 
except  the  rotation  which  favors  the  motion  of  the  sternum ;  and 
that  the  lower  ribs,  having  no  support  at  their  anterior  extremi- 
ties, have  no  rotation. 


The  Pelvis. 

The  pelvis  is  the  cavity  at  the  lower  part  of  the  trunk,  formed 
by  the  os  sacrum,  os  coccygis,  and  ossa  innominata. 


164 


OS    ILIUM. 


The  ossa  innominata  are  the  two  large  bones  which  are  con- 
nected to  the  sacrum  behind,  and  to  each  other  by  the  interven- 
tion of  a  cartilage  in  front. 

Each  of  the  ossa  innominata  is  composed  of  three  portions,  in 
children  ;  and  although  these  are  united  in  adults,  so  as  to  form 
but  one  bone,-  yet  anatomists  have  generally  considered  the  bone 
as  divided  into  its  original  parts,  which  are  denominated  os  ilium, 
os  ischium,  and  os  pubis. 

The  original  separation  was  at  the  acetabulurn,  or  cavity  for 
receiving  the  head  of  the  os  femoris,  which  is  on  the  outside  o{ 
the  os  innominatum.  The  upper  and  posterior  part  of  this  cavity, 
to  the  amount  of  two-fifths,  is  formed  by  the  os  ilium,  two-fifths 
of  the  inferior  portion  by  the  os  ischium,  and  the  anterior  fifth 
by  the  os  pubis. 

The  Os  Ilium 

Fig.  39.*  Is  the  largest  of  the  three 

portions.  Its  external  sur- 
face has  been  called  its 
dorsum,  and  the  internal 
concave  surface  its  costa  or 
venter.  The  semicircular 
edge  at  the  upper  part  of  the 
bone,  is  named  the  spine  or 
crest;  the  external  oblique 
muscle  of  the  abdomen  is  in- 
serted into  it,  and  the  inter- 
nal oblique,  and  the  transver- 
salis  arise  from  it.  The  ends 
of  the  spine  are  prominent, 
and  therefore  are'called  pro- 

*  The  os  innominatura  of  the  right  side.  1.  The  ilium  ;  its  external  surface. 
2.  The  ischium.  3.  The  os  pubis.  4.  The  crest  of  the  ilium.  5.  The  superior 
curved  line.  6.  The  inferior  curved  line.  7.  The  surface  for  the  glutens  maxi- 
mus.  8.  The  anterior  superior  spinous  process.  9.  The  anterior  inferior  spinous 
process.  10.  The  posterior  superior  spinous  process.  11.  The  posterior  inferior 
spinous  process.  12.  The  spine  of  the  ischium.  13.  The  great  sacro-ischiatic 
notch.  14.  The  lesser  sacro-ischiatic  notch.  15.  The  tuberosity  of  the  ischiurfij 
showing  its  four  surfaces.  16.  The  ramus  of  the  ischium.  17.  The  body  of  the 
os  pubis.  18.  The  ramus  of  the  pubis. 


OS    ILIUM.  165 

cesses.  In  front  the  crest  terminates  in  the  anterior  superior 
spinous  process ;  below  this  is  another  protuberance,  called 
the  inferior  anterior  spinous  process  ;  and  the  edge  of  the  bone 
between  these  two  processes  is  curved. 

Behind  the  crest  terminates  in  the  posterior  superior  spinous 
process ;  below  this  another  protuberance  is  also  observable, 
(post.  inf.  spin,  process)  which  is  applied  closely  to  the  os 
sacrum.  Under  this  is  a  large  notch,  which,  with  the  ligaments 
that  pass  from  the  os  sacrum  to  the  os  ischium,  forms  a  foramen, 
through  which  the  great  sciatic  nerve,  the  pyriform  muscle, 
and  some  blood-vessels  pass. 

The  external  surface,  or,  dorsum,  of  the  os  ilium,  is  greatly 
undulated  by  the  action  of  muscles  that  lie  upon  it ;  the  gluteus 
maximus,  on  the  posterior,  and  the  gluteus  medius  and  minimus, 
on  the  anterior  parts  of  it.  The  lower  part  of  this  bone,  which 
contributes  to  the  formation  of  the  acetabulum,  is  the  thickest. 

The  internal  surface  of  the  os  ilium  is  concave,  and  supports 
some  of  the  intestines.  From  this  concave  surface  a  slight  con- 
cavity is  continued  obliquely  forwards,  at  the  inside  of  the 
anterior  inferior  spinous  process,  where  part  of  the  psoas  and 
iliacus  muscles,  with  the  crural  vessels  and  nerves  pass.  The 
large  concavity  is  bounded  below  by  a  sharp  ridge,  which  runs 
from  behind  forwards ;  and,  being  continued  with  such  another 
ridge  of  the  os  pubis,  forms  a  line  of  partition  between  the 
cavities  of  the  abdomen  and  pelvis.  Into  this  ridge  called  linea 
ilia  innominata  the  broad  tendon  of  the  psoas  parvus  is 
inserted. 

All  the  internal  surface  of  the  os  ilium,  behind  the  continu- 
ance of  this  ridge,  is  very  unequal :  for  the  upper  part  is  flat, 
but  spongy,  where  the  sacro-lumbalis  and  longissimus  dorsi 
rise.  Lower  down,  there  is  a  transverse  ridge  from  which 
ligaments  go  out  to  the  os  sacrum.  Immediately  below  this 
ridge,  the  rough  unequal  cavities  and  prominences  are  placed, 
which  are  exactly  adapted  to  those  described  on  the  side  of  the 
os  sacrum.  In  the  same  manner,  the  upper  part  of  this  rough 
surface  is  porous,  for  the  firmer  adhesion  of  the  ligamentous 
cellular  substance  ;  while  the  lower  part  is  more  solid,  and 
covered  with  a  thin  cartilaginous  skin,  for  its  immovable  arti- 


166  OS    ISCHIUM. 

culation  with  the  os  sacrum.  From  all  the  circumference  of 
this  large  unequal  surface,  ligaments  are  extended  to  the  os 
sacrum,  to  secure  more  firmly  the  conjunction  of  these  bones. 

The  passages  of  the  medullary  vessels  are  very  conspicuous, 
both  in  the  dorsum  and  costa  of  many  ossa  ilia  ;  but  in  others 
they  are  inconsiderable. 

The  posterior  and  lower  parts  of  these  bones  are  thick;  but 
they  are  generally  exceeding!^  thin  and  compact  at  their 
middle,  where  they  are  exposed  to  the  actions  of  the  musculi 
glutaei  and  iliacus  internus,  and  to  the  pressure  of  the  bowels 
contained  in  the  belly.  The  substance  of  the  ossa  ilia  is  cellu- 
lar, except  a  thin  external  plate. 

The  Os  Ischium, 

Or,  hip-bone,  is  of  a  middle  size,  between  the  two  other  parts 
of  the  os  innominatum,  and  of  a  very  irregular  figure.  Its 
extent  might  be  marked  by  a  horizontal  line  drawn  a  little 
below  the  middle  of  the  acetabulum ;  for  the  upper  bulbous 
part  of  this  bone  forms  rather  less  than  the  lower  half  of  that 
great  cavity,  and  the  small  leg  of  it  rises  to  much  the  same 
height  on  the  other  side  of  the  great  hole  common  to  this 
bone  and  the  os  pubis. 

From  the  upper  thick  part  of  the  os  ischium,  a  sharp  process, 
called  by  some  authors  spinousj  stands  out  backwards,  from 
which  chiefly  the  musculus  coccygaeus  and  superior  gemellus, 
and  part  of  the  levator  ani,  rise ;  and  the  anterior,  or  internal 
sacro-sciatic  ligament  is  fixed  to  it.  Between  the  upper  part 
of  this  ligament  and  the  bones,  it  was  formerly  observed,  that 
the  pyriform  muscle,  the  posterior  crural  vessels,  and  the 
sciatic  nerve,  pass  out  of  the  pelvis.  Immediately  below  this 
process,  is  a  depression  for  the  tendon  of  the  obturator  internus 
muscle.  In  a  recent  subject,  this  part  of  the  bone  serves  as  a 
pulley  on  which  the  obturator  muscle  plays  with  a  ligamentous 
cartilage. 

Below  the  depression  of  the  obturator  muscle,  is  the  great 
knob  or  tuberosity,  covered  with  cartilage  or  tendon.  The 
upper  part  of  the  tuberosity  gives  rise  to  the  inferior  gemellus 


os  PUBIS.  167 

muscle.  To  a  ridge  at  the  inside  of  this,  the  external,  or  pos- 
terior sacro-sciatic  ligament  is  so  fixed,  that  between  it,  the 
internal  ligament,  and  the  sinuosity  of  the  os  ischium,  a  passage 
is  left  for  the  internal  obturator  muscle.  The  upper  thick 
smooth  part  of  the  tnber,  called  by  some  its  dorsum,  has  two 
oblique  impressions  on  it.  The  inner  one  gives  origin  to  the 
long  head  of  the  biceps  flexor  cruris,  and  semitendinosus 
muscles ;  and  the  semimembranosus  rises  from  the  exterior  one, 
which  reaches  higher  and  nearer  the  acetabulum  than  the 
other.  The  lower,  thinner,  more  scabrous  part  of  the  knob, 
which  bends  forwards,  is  also  marked  with  two  flat  surfaces ; 
whereof  the  internal  is  what  we  lean  upon  in  sitting,  and  the 
external  gives  rise  to  the  largest  head  of  the  triceps  adductor 
femoris.  Between  the  external  margin  of  the  tuberosity,  and 
the  great  hole  of  the  os  innominatum,  there  is  frequently  an 
obtuse  ridge  extended  down  from  the  acetabulum,  which 
gives  origin  to  the  quadratus  femoris.  As  the  tuber  advances 
forwards,  it  becomes  smaller,  and  is  rough  for  the  origin  of  the 
musculus  transversalis  and  erector  penis.  The  small  leg  of  it, 
which  mounts  upwards  to  join  the  os  pubis,  is  rough  and  prom- 
inent at  its  edge,  where  the  two  lower  heads  of  the  triceps 
adductor  femoris  take  their  rise. 

The  upper  and  back  part  of  the  os  ischium  is  broad  and 
thick  ;  but  its  lower  and  forepart  is  narrower  and  thinner.  Its 
substance  is  of  the  structure  common  to  broad  bones. 

The  os  ilium  and  pubis,  of  the  same  sides,  are  the  only 
bones  which  are  contiguous  to  the  os  ischium. 

The  Os  Pubis, 

The  least  of  the  three  portions  of  the  os  innominatum,  is 
placed  at  the  upper  and  front  part  of  it.  The  thick,  largest 
part  of  this  bone  is  employed  in  forming  the  acetabulum  ;  from 
which,  becoming  much  smaller,  it  is  stretched  inwards  to  its 
fellow  of  the  other  side,  where  it  again  grows  larger,  and 
forms  a  surface  to  be  connected  with  the  cartilage  of  its  sym- 
physis  and  then  sends  a  small  branch  downwards  to  join  the 


168  os  PUBIS. 

end  of  the  small  leg  of  the  os  ischium.  The  upper  surface  of 
each  os  pubis  is  broad,  near  its  junction  with  the  cartilage  of 
the  symphysis ;  on  the  internal  edge  of  this  surface  begins  a 
ridge,  which  is  continued  from  it  along  the  os  ilium,  and  forms 
the  division  between  the  cavities  of  the  abdomen  and  pelvis. 
This  ridge  is  called  crista,  and  including  that  on  the  ilium,  forms 
the  linea  innominata,  or  ileo-pectinea.  On  the  anterior  and  ex- 
ternal edge  of  this  surface  of  the  pubis,  at  a  small  distance  from 
the  cartilage,  is  a  prominence  or  process,  called  the  spine.  From 
this  process,  another  ridge,  which  is  much  more  obtuse,  extends 
to  the  acetabulum.  The  upper  surface  of  the  pubis,  which  is 
included  between  these  ridges,  is  concave,  for  the  transmission 
of  the  crural  vessels  and  nerve,  and  the  psoas  and  iliacus 
internus  muscles. 

Immediately  below  the  lower  ridge,  and  near  the  acetabu- 
lum, a  winding  notch  is  made,  which  is  comprehended  in  the 
great  contiguous  foramen  ;  but  is  formed  into  a  hole  in  the 
recent  subject  by  a  subtended  ligament,  for  the  passage  of  the 
posterior  crural  nerve,  and  artery,  and  vein.  The  internal  end 
of  the  os  pubis  is  rough  and  unequal,  for  the  firmer  adhesion 
of  the  thick  ligamentous  cartilage  that  connects  it  to  its  fellow 
of  the  other  side.  The  process  which  goes  down  from  that  to 
the  os  ischium  is  broad  and  rough  before,  where  the  gracilis 
and  upper  heads  of  the  triceps  adductor  femoris  have  their 
origin. 

The  substance  of  the  os  pubis  is  the  same  as  that  of  other 
broad  bones. 

Between  the  os  ischium  and  pubis  a  very  large  irregular  hole 
is  left,  which  has  been  called  obturator,  thyroid.  The  whole  of 
this  foramen,  except  the  notch  for  the  posterior  crural  nerve,  is 
filled  up,  in  a  recent  subject,  with  a  strong  ligamentous  mem- 
brane, that  adheres  very  firmly  to  its  circumference.  From 
this  membrane  chiefly,  the  two  external  and  internal  obturator 
muscles  take  their  rise.  The  great  design  of  this  hole,  besides 
rendering  the  bone  lighter,  is,  to  allow  a  strong  origin  to  the 
obturator  muscles,  and  sufficient  space  for  lodging  them  ;  that 
there  may  be  no  danger  of  disturbing  the  functions  of  the  con- 


ACETABULUM.  169 

tained  viscera  of  the  pelvis  by  the  actions  of  the  internal ;  nor 
of  the  external  being  bruised  by  the  thigh  bone,  especially  by 
its  lesser  trochanter,  in  the  motions  of  the  thigh  inwards  :  both 
which  inconveniences  must  have  happened,  had  the  ossa  mnom- 
inata  been  complete  here,  and  of  sufficient  thickness  and 
strength,  as  the  fixed  point  of  these  muscles. 

The  bowels  sometimes  make  their  way  through  the  notch 
for  the  vessels  at  the  upper  part  of  this  thyroid  hole  ;  and  this 
causes  a  hernia  at  this  place. 

The  acetabulum  is  situated  near  the  outside  of  the  great 
foramen.  The  margin  of  this  cavity  is  very  high,  and  is  still 
much  more  enlarged  by  the  ligamentous  cartilage,  with  which 
it  is  tipped  in  a  recent  subject;  round  the  base  of  this  margin 
the  bone  is  rough  and  unequal,  where  the  capsular  ligament  of 
the  articulation  is  fixed.  At  the  upper  and  back  part  of  the 
acetabulum  the  margin  is  much  larger  and  higher  than  any 
where  else ;  which  is  very  necessary  to  prevent  the  head  of  the 
femur  from  slipping  out  of  its  cavity  at  this  place,  where  the 
whole  weight  of  the  body  bears  upon  it,  and  consequently 
might  otherwise  thrust  it  out.  As  the  margin  is  extended 
downwards  and  forwards,  it  becomes  less ;  and,  at  the  internal 
lower  part,  is  a  deficiency  in  it ;  from  the  one  side  of  which  to 
the  other,  a  ligament  is  placed  in  the  recent  subject,  under 
which  a  large  hole  is  left.  Besides  this  difference  in  the  height 
of  the  margin,  the  acetabulum  is  otherwise  unequal ;  for  the 
lower  internal  part  of  it  is  depressed  below  the  cartilaginous 
surface  of  the  upper  part,  and  is  not  covered  with  cartilage ; 
into  the  upper  part  of  this  particular  depression,  where  it  is 
deepest,  and  of  a  semilunar  form,  the  ligament  of  the  thigh 
bone,  commonly,  though  improperly  called  the  round  one,  is 
inserted :  while,  in  its  more  superficial  lower  part,  a  mass  of 
adipose  matter  is  lodged.  The  greatest  part  of  this  separate 
depression  is  formed  in  the  os  ischium. 

The  ossa  innominati  are  joined,  at  their  back  part,  to   each 

side  of  the   os  sacrum,  by  a  sort  of  suture,  with    a   very  thin 

intervening    cartilage,    which    serves    to    cement    these    bones 

together:  and   strong  ligaments   go  from    the  circumference  of 

15 


170  CAVITY  OF  THE  PELVIS. 

this  unequal  surface  to  connect  them  more  firmly.  They  are 
connected  together  at  their  forepart  by  the  ligamentous  cartilage 
interposed  between  the  two  ossa  pubis,  and  therefore  have  no 
motion  in  a  natural  sjate,  except  what  is  common  to  the  trunk 
of  the  body,  or  to  the  os  sacrum. 

Considering  the  great  weight  that  is  supported  in  our  erect 
posture,  by  the  articulation  of  the  ossa  innominati  with  the  os 
sacrum,  there  is  great  reason  to  think,  that,  if  the  conglutinated 
surfaces  of  these  bones  were  once  separated,  (without  which 
the  ossa  pubis  cannot  move  on  each  other,)  the  ligaments 
would  be  violently  stretched,  if  not  torn. 

Each  os  innominatum  affords  a  socket  (the  acetabulum)  for 
the  thigh  bones  to  move  in ;  and  the  trunk  of  the  body  rolls  so 
much  on  the  heads  of  the  thigh  bones  as  to  allow  here  the  most 
conspicuous  motions  of  the  trunk,  which  are  commonly  thought 
to  be  performed  by  the  bones  of  the  spine. 

The  form  of  the  cavity  of  the  pelvis,  at  its  upper  opening,  or 
brim,  is  somewhat  oval  ;  as  a  line  drawn  from  one  side  to  the 
other,  is  about  an  inch  longer  than  a  line  drawn  from  the  back 
to  the  front  part  of  it. 

This  margin  is  well  defined  by  the  ridge  on  the  surface  of 
the  ossa  ilia,  and  the  upper  edge  of  the  os  pubis ;  but  the 
margin  of  the  lower  opening  is  very  irregular  ;  and  it  ought  to 
be  observed,  that  the  dimensions  of  this  opening  are  made  less 
by  the  sacro-sciatic  ligaments,  than  they  appear  upon  an 
examination  of  the  bare  bones. 

In  consequence  of  the  oblique  position  of  the  sacrum, 
sloping  downwards  and  backwards,  the  position  of  the  pelvis 
is  very  oblique.  A  line  drawn  through  the  centre  of  this 
cavity,  perpendicular  to  the  plane  of  the  upper  orifice,  or  brim, 
would  not  coincide  with  the  vertical  diameter  of  the  cavity  of 
the  abdomen,  but  would  pass  out  of  that  cavity  near  the 
umbilicus. 

This  cavity,  and  the  bones  which  form  it,  are  different  in  the 
two  sexes. 

In  women,  the  brim  of  the  pelvis  is  wider,  and  inclines  more 
to  the  oval  form. 

In  men  this  opening  is  more  circular. 


CAVITY  OF  THE  PELVIS.  171 

The  outlet  or  lower  opening  of  the   pelvis   is   also  larger  in 
women. 

This  greater  size  of  the  pelvis  and  its  openings,  in  women,  is 
derived  particularly  from  the  following  circumstances  : 

The  os  sacrum  is   broader,  and   sometimes  straighter  than  in 
men. 

The  ossa  ilia  are  flatter,  and  consequently  the  ossa  ischia  are 
farther  apart. 

The  ligamentous  cartilage  at  the  symphysis  pubis  is  broader, 
and  shorter. 

The  angle  formed  by  the  crura  of  the  ossa  pubis  with  each 
other,  at  the  symphysis,  is  much  larger. 

— The  pelvis,  considered  as  a  whole,  is  very  irregular,  though 
symmetrical  in  its  shape.  It  has  the  form  of  a  truncated  cone, 
or  a  funnel  with  its  base  upwards,  curved  from  behind  forward 
with  its  concavity  in  front,  and  is  bounded  both  above  and 
below  by  bony  walls  of  unequal  elevation.  It  is  divided  by  the 
projection  of  the  base  of  the  sacrum  and  the  two  ilio-pectineal 
lines,  into  a  greater  and  lesser  pelvis,  the  former  of  which  is 
above.  The  dividing  line  is  called  the  superior  strait  of  the 
lesser  pelvis.  The  bony  walls  of  the  greater  pelvis  is  incom- 
plete. The  boundaries  of  this  cavity,  are  formed  upon  the 
sides  by  the  iliac  fossa?,  and  behind  by  a  notch  which  is  nearly 
filled  up,  when  the  last  lumbar  vertebrae  is  left  connected  with 
the  sacrum  ;*  and  in  front  by  all  the  wide  triangular  opening  be- 
tween the  anterior  superior  spine  of  the  ^lium  of  each  side  and 
the  symphysis  pubis'which  is  filled  up  by  the  lower  part  of  the 
abdominal  muscles.  From  the  flaring  direction  of  the  upper 
part  of  the  ilia,  the  diameters  of  the  base  of  this  cavity,  or  that 
towards  the  abdomen,  is  greater  than  those  opposite  the  ilio- 
pectineal  lines. 

— The  lesser  pelvis,  forms  nearly  an  entire  bony  canal,  and 
which  the  student  is  too  apt  to  consider  as  constituting  the  whole 
pelvis.  This  cavity  is  larger  at  its  middle  than  at  its  extremities. 
It  is  bounded  behind  by  the  sacrum  and  coccyx ;  in  front  by  the 

*  The  attachment  of  the  lumbar  muscles  completes  this  wall  behind. 

j,   ,-f? 


to      ^^L^Lr 


172  DIMENSIONS  OF  THE  PELVIS. 

symphysis  pubis  and  a  part  of  the  obturator  foramen  ;  and  upon 
the  sides,  by  the  bony  surface  which  corresponds  to  the  cotyloid 
cavity.  Its  superior  margin  (superior  strait,)  is  regular  and 
ovoidal  in  its  shape.  Its  longest  diameter  is  transverse.  Its 
inferior  strait  is  very  irregular,  though  symmetrical  in  the  form 
of  its  bony  walls  ;  and  in  consequence  of  the  posterior  walls  of 
this  pelvis  being  of  much  greater  length  than  the  anterior, 
presents  an  oblique  cut,  which  faces  slightly  forwards, 
so  that  if  its  axis  was  extended  downwards,  it  would 
cross  just  above  the  middle  of  the  thigh.  It  is  bounded 
behind,  by  the  point  of  the  coccyx  ;  in  front,  by  the  sym- 
physis pubis ;  and  on  the  side,  by  the  tuberosities  of  the 
ischium.  The  sacro-sciatic  notches  and  the  arch  of  the  pubis, 
are  filled  up  by  ligaments  and  soft  parts.  From  the  general 
form  of  the  whole  pelvic  cavity  it  will  then  be  obvious,  that  a 
body  passing  through  its  axis  from  above  downwards,  must 
advance  successively  in  three  directions :  1st,  as  it  passes 
through  the  greater  pelvis,  obliquely  backwards  ;  2d,  vertically  ; 
and  3d,  as  it  passes  through  the  inferior  strait,  obliquely 
forwards. 

— For  obstetrical  purposes,  it  is  necessary  for  the  student  to 
have  precise  notions  in  regard  to  the  dimensions  of  the  pelvis. 
To  determine  this,  it  is  necessary  to  measure  the  superior 
opening  of  the  greater  pelvis,  and  the  two  straits  of  the 
lesser. 

— The  pelvis  of  the  male,  differs  in  many  respects  from  that  of 
the  female.  In  the  former  length  predominates,  in  the  latter, 
breadth.  In  the  female  all  the  diameters  of  the  pelvis  are  more 
extensive  than  those  of  the  male,  which  is  caused  by  the  greater 
size  and  outward  direction  of  the  iliac  fossae,  from  a  less  degree 
of  curvature  in  the  iliac  crests,  and  from  the  roundness  of  the 
pubic  arch  which  in  the  male  forms  an  acute  angle.  In  conse- 
quence of  the  wider  space  which  exists  between  -the  cotyloid 
cavities,  the  gait  of  the  female  is  characterized  by  more  lateral 
rotation  or  waddling,  than  that  of  man.  A 

— In  a  well  formed  woman,  the  different  measurements  are 
nearly  as  follows  : 


TRUNK  OF    THE    FOETUS.  173 

Greater  Pelvis. 

- — In  the  superior  opening  of  the  greater  pelvis,  we  distinguish 
but  two  diameters,  both  transverse.  The  posterior  extended 
from  the  middle  of  one  iliac  crest  to  the  other,  eleven  mches. 
The  anterior,  between  the  two  anterior  superior  spinous  processes 
of  the  ilium,  ten  inches.  From  the  middle  of  the  iliac  crest,  to 
the  superior  strait,  three  and  a  half  inches.  From  the  middle 
of  the  iliac  crest  to  the  tuberosity  of  the  ischium,  (whole  depth 
of  the  pelvis)  seven  and  a  half  inches  nearly.* 

Lesser  Pelvis. 

Superior  Strait,  sometimes  called  ab-  Inferior  Strait,  or  perineaL 

dominal. 

Inches.  Inches. 

Antero-posUrior  diameter,  from  Antero-posterior  diameter,  be- 

the  symphysis  of  the  pubis  to  the  tween  the  symphysis  pubis  andS 

promontory  of  the  sacrum,  -    -     4     front  of  the  coccyx,  which  may  be 
Transverse,    or    iliac,    which  increased  near  an  inch  by  the  mo- 

crosses  the  former,   at   a  right  bility  of  the  coccyx  backwards,        4 

angle,       ------      5          Transverse,   or  ischiatic,  from 

Oblique,  from  the  acetabulum  of  one  tuberosity  of  the  ischium  to 

one  side,  to  the  sacro-iliac,  articu-  the  other,        -----      4 

Lation  of  the  other,       -      -      -    4.J.        Oblique,  from  the  tuberosity  of 

the  ischium  of  one  side,  to  the  mid- 
dle of  the  great  sacro  sciatic  liga- 
ment of  the  other,  nearly  4 

The  height  of  the  posterior  wall  of  the  lesser  pelvis, 
formed  by  the  sacrum  and  coccyx,  (of  which  the 

latter  forms  an  inch,)  is  nearly  -  -  5  inches. 

Height  of  the  anterior  wall  formed  by  the  os  pubis,  1|  " 

Height  of  the  lateral  walls,  -  -  3J  " 

Thickness  of  the  symphysis  pubis,  about  -  \  " 

Depth  or  sine  of  the  cavity  of  the  sacrum,f  nearly  -  I  " 

The  Trunk  of  the  Fcstus. 
At  birth,  each  vertebra  consists  of  three  pieces,  connected  by 

*  The  depth  or  length  of  the  pelvis  is  rather  greater  in  the  male  than  in  the 
female. 

f  Dimensions  of  the  child's  head  at  birth.  The  long  diameter,  from  the 
vertex  or  posterior  extremity  of  the  sagittal  suture  to  the  chin,  5  1-4  inches  ; 
antero- posterior,  from  the  middle  of  the  frontal  bone  to  the  tubercle  of  the 
occipital,  4  inches;  transverse,  from  one  parietal  protuberance  to  the  other, 
3  1-2  inches. 

15* 


174  THE    SUPERIOR    EXTREMITIES. 

cartilages,  viz. :  The  body,  not  perfectly  ossified ;  and  a  bone  on 
each  side  of  it,  of  a  form  almost  rectangular,  on  which  the  oblique 
processes  are  very  distinguishable,  and  the  transverse  processes 
may  be  ascertained.  These  bones  are  so  applied  to  the  body, 
as  to  include  a  triangular  space  for  the  vertebral  cavity.  The 
ends  of  the  longest  portions  are  nearly  in  contact  behind  ;  but 
the  spinous  process  is  not  formed.  The  atlas  is  cartilaginous  in 
front,  and  has  only  the  two  late?al  portions  ossified.  The  verte- 
bra dentata  consists  of  four  pieces  ;  for,  in  addition  to  the  three 
pieces  common  to  the  other  vertebrae,  the  processus  dentatus  is  a 
distinct  portion. 

The  false  vertebra,  of  which  the  sacrum  consists,  are  each 
formed  of  three  bones  as  the  true  vertebras. 

The  bones  of  the  os  coccygis  are  cartilaginous,  except  the 
first,  which  is  partly  ossified. 

The  ribs  are  almost  perfect  at  birth  :   their  heads  and  tuber- 
cles covered  with  cartilage.     The  necessity  of  their  motion   in 
respiration,  immediately  after  birth,  explains   this  difference  be 
tween  them,  and  most  of  the  other  bones  of  the  foetus. 

The  sternum  consists  of  several  small  bones,  surrounded  by 
flat  cartilages.  Ossification  goes  on  in  these  cartilages  from 
various  points  ;  and  the  distinct  bones  finally  unite  into  the  three 
pieces  of  which  the  sternum  is  finally  composed. 

The  ossa  innominata,  on  each  side,  are  formed  of  three  dis- 
tinct pieces,  united  at  the  acetabulum. 

The  spine  of  the  os  ilium  is  cartilaginous  ;  and  the  lower  part 
of  the  bone  is  not  completely  ossified. 

The  back  part  of  the  os  ischium  is  ossified  ;  but  the  portion 
which  forms  the  acetabulum,  the  tuber,  and  the  crus,  is  cartila- 
ginous. 

The  upper  part  of  the  os  pubis,  and  that  portion  which  forms 
the  symphysis,  are  ossified.  The  crus,  like  that  of  the  ischium, 
is  cartilaginous. 

Of  the  Superior  Extremities. 

Each  superior  extremity  consists  of  the  SHOULDER,  the  ARM, 
the  FOREARM,  and  the  HAND. 


THE     CLAVICLE.  175 

The  shoulder  is  composed  of  the  clavicle  and  scapula.  It  has 
been  supposed  by  some  persons  that  the  two  last  mentioned 
bones  belong  properly  to  the  thorax  ;  but  upon  examining  the 
motions  of  the  upper  extremity,  it  will  appear  that  they  fdrm  an 
essential  part  of  it :  and  it  is  equally  evident  that  they  do  not 
contribute  to  the  perfection  of  the  thorax ;  they  are,  therefore, 
considered  as  a  part  of  the  upper  extremity. 

The  Clavicle^ 

Is  the  long  crooked  bone  resembling  the  italic  /,  which  is 
placed  almost  horizontally  between  the  upper  lateral  part  of  the 
sternum  and  the  acromion,  or  most  prominent  process  of  the 
scapula  which  it  keeps  off  from  the  trunk  of  the  body. 

The  clavicle,  as  well  as  other  long  bones,  is  larger  at  its  two 
ends  than  in  the  middle.  The  end  next  to  the  sternum  is  trian- 
gular ;  the  angle  behind  is  considerably  protruded,  to  form  a 
sharp  ridge,  to  which  the  transverse  ligament,  extended  from  one 
clavicle  to  the  other,  is  fixed.  The  side  opposite  to  this  is  some- 
what rounded.  The  middle  of  this  protuberant  end  is  irregularly 
hollowed,  as  well  as  the  cavity  in  the  sternum  for  receiving  it : 
but,  in  a  recent  subject,  the  irregular  concavities  of  both  are 
supplied  by  a  movable  cartilage  ;  which  is  not  only  much  more 
closely  connected  every  where,  by  ligaments,  to  the  circumference 
of  the  articulation,  than  those  of  the  lower  jaw  are,  but  it  grows 
to  the  two  bones  at  both  its  internal  and  external  end ;  its  sub- 
stance at  the  external  end  being  soft,  but  very  strong,  and 
resembling  the  intervertebral  cartilages. 

From  its  internal  end,  the  clavicle,  for  about  two-fifths  of  its 
length  is  bended  obliquely  forwards.  On  the  upper  and  front 
part  of  this  curvature  a  small  ridge  is  seen,  with  a  plane  rough 
surface  before  it ;  whence  the  sterno-hyoideus  and  sterno-mas- 
toideus  muscles  have  in  part  their  origin.  Near  the  lower  angle, 
a  small  plane  surface  is  often  to  be  remarked,  where  the  first 
rib  and  this  bone  are  contiguous,  and  are  connected  by  a  firm 
ligament.  From  this  a  rough  plane  surface  is  extended  outwards, 
where  the  pectoral  muscle  has  part  of  its  origin.  Behind,  the 
bone  is  made  flat  and  rough  by  the  insertion  of  the  larger 


176  THE    CLAVICLE. 

share  of  the  subclavian  muscle.  The  clavicle  is  then  curved 
backwards,  and  at  first  is  round ;  but  it  soon  after  becomes  broad 
and  thin  ;  which  shape  it  retains  to  its  external  end.  Along  the 
external  concavity  a  rough  sinuosity  runs  ;  from  which  some  part 
of  the  deltoid  muscle  takes  its  rise  :  opposite  to  this,  on  the  con- 
vex edge,  a  scabrous  ridge  gives  insertion  to  a  share  of  the 
trapezius  muscle.  The  upper  surface  of  the  clavicle  is  here  flat ; 
but  the  lower  is  hollow,  for  lodging  the  beginning  of  the  musculis 
subclavius  ;  and  towards  its  back  part  a  tubercle  rises  ;  to  which, 
and  to  a  roughness  near  it,  the  strong,  short,  thick  ligament, 
connecting  this  bone  to  the  coracoid  process  of  the  scapula,  is 
fixed. 

The  external  end  of  this  bone  is  oblong  horizontally,  smooth, 
sloping  at  the  posterior  side,  and  tipped  in  a  recent  subject  with 
a  cartilage,  for  its  articulation  with  the  acromion  scapulae. 
Round  this  the  bone  is  spongy,  for  the  firmer  connexion  of  the 
ligaments. 

The  surfaces  of  contact  with  this  bone,  and  the  scapula  are 
remarkably  small,  and  flat  also. 

The  medullary  arteries,  having  their  direction  obliquely  out- 
wards, enter  the  clavicles  by  one  or  more  small  passages  in  the 
middle  of  their  back  part. 

The  substance  of  this  bone  is  the  same  as  that  of  the  other 
round  long  bones. 

The  ligaments  which  surround  the  articulation  of  this  bone 
with  the  sternum,  are  so  short  snd  strong,  that  little  motion  can 
be  allowed  any  way  ;  and  the  strong  ligament  that  is  stretched 
across  the  upper  forcula  of  the  sternum,  from  the  posterior 
prominent  angle  of  the  one  clavicle  to  the  same  place  of  the 
other  clavicle,  serves  to  keep  each  of  these  bones  more  firmly 
in  its  place.  By  the  assistance,  however,  of  the  movable  inter- 
vening cartilage,  the  clavicle  can  move  at  this  articulation,  so 
that  the  external  extremity  may  be  elevated  or  depressed,  and 
moved  backwards  and  forwards.  The  whole  bone  may  be 
moved  so  as  to  describe  a  cone  ;  of  which  the  end  at  the  sternum 
is  the  apex. 

The  movements  of  the  scapula  and  arm  are  the  objects  of 


THE    SCAPULA.  177 

these  motions  of  the  clavicle  ;  and  the  general  use  of  the  bone 
is  to  regulate  the  motions  of  these  parts. 

From  the  situation,  figure,  and  use  of  the  clavicles,  it  is  evident 
that  they  are  much  exposed  to  fractures ;  that  their  broken 
parts  must  generally  pass  each  other,  and  that  they  will  be  kept 
in  their  places  with  difficulty. 

The  Scapula, 

Or  shoulder-Hade ,  is  the  triangular  bone  situated  on  the  upper 
and  back  part  of  the  thorax.     The  back  part  of  the  scapula  has 
Fig.  40.*  nothing  but  the  thin  ends  of  the 

ser/atus  anticus  major,  and  sub- 
scapularis  muscles  between  it 
and  the  ribs:  but  as  this  bone 
advances  forwards,  its  distance 
from  the  ribs  increases.  The 
longest  side  of  this  bone  is  near- 
est the  spine,  and  has  an  oblique 
position  as  respects  it.  The  up- 
per or  shortest  side,  called  the 
superior  costa  of  the  scapula,  is 
nearly  horizontal,  and  parallel 
with  the  second  rib.  The  lower 
.side,  which  is  named  the  inferior 
costa,  is  extended  obliquely  from 
the  third  to  the  eighth  rib.  The 
situation  of  this  bone,  here  described,  is,  as  when  people  are  sit- 
ting or  standing,  in  a  state  of  inactivity,  and  allowing  the  mem- 
bers to  remain  in  the  most  natural  easy  posture.  The  inferior 
angle  of  the  scapula  is  very  acute  ;  the  upper  one  is  near  to  a 


*  A  posterior  view  of  the  scapula.  1.  The  supra-spinous  fossa.  2.  The  infra- 
spinous  fossa.  3.  The  superior  border.  4.  The  supra-scapular  notch.  5.  The 
anterior  or  inferior  border.  6.  The  head  of  the  scapula  and  glenoid  cavity.  7. 
The  inferior  angle.  8.  The  neck  of  the  scapula,  the  ridge  opposite  the  number 
gives  origin  to  the  long  head  of  the  triceps.  9.  The  posterior  border  or  base  of 
the  scapula.  10.  The  spine.  11.  The  triangular  smooth  surface,  over  which 
the  tendon  of  the  trapezius  glides.  12.  The  acromion  process.  13.  One  of  the 
nutritious  foramina.  14.  The  coracoid  process. 


178  THE    SCAPULA. 

right  angle ;  and  what  is  called  the  anterior  does  not  deserve 
the  name,  for  the  two  sides  do  not  meet  to  form  an  angle.  The 
body  of  this  bone  is  concave  towards  the  ribs,  and  convex 
behind,  where  it  has  the  name  of  dorsum.  Three  processes  are 
generally  reckoned  to  proceed  from  the  scapula.  The  first  is  the 
large  spine  that  rises  from  its  convex  surface  behind,  and  divides 
it  unequally.  The  second  process  stands  out  from  the  forepart 
of  the  upper  side;  and,  from  its  imaginary  resemblance  to  a 
crow's  beak,  is  named  coracoides.  The  third  process  is  the 
whole  thick  bulbous  forepart  of  the  bone. 

Into  the  oblique  space  the  musculis  patientia  (levator  scapul<z) 
is  inserted.  At  the  root  of  the  spine,  on  the,  back  part  of  the 
base,  a  triangular  flat  surface  is  formed  by  the  pressure  of  the 
lower  fibres  of  the  trapezius.  Below  this,  the  edge  of  the 
scapula  is  scabrous  and  rough,  for  the  insertion  of  the  serratus 
major  anticus  and  rhomboid  muscles. 

The  back  part  of  the  inferior  angle  is  made  smooth  by  the 
latissimus  dorsi  passing  over  it.  The  muscle  also  alters  the 
direction  of  the  inferior  costa  some  way  forwards  from  this  angle  : 
and  so  far  it  is  flattened  behind  by  the  origin  of  the  teres  major. 
As  the  inferior  costa  advances  forward,  it  is  of  considerable 
thickness,  is  slightly  hollowed,  and  made  smooth  behind,  by  the 
teres  minor ;  while  it  has  a  fossa  formed  into  it  below,  by  part 
of  the  subscapularis  ;  and  between  the  two,  a  ridge  with  a  small 
depression  appears,  where  the  extensor  longus  cubiti  has  its 
origin. 

The  superior  costa  is  very  thin  ;  and  near  its  forepart  there 
is  a  semi-lunar  notch,  from  one  end  of  which  to  the  other,  a 
ligament  is  stretched ;  and  sometimes  the  bone  is  continued  to 
form  one,  or  sometimes  two  holes,  for  the  passage  of  the  scapular 
blood-vessels  and  nerves.  Immediately  behind  this  semilunar 
cavity,  the  coraco-hyoideus  muscle  has  its  rise.  From  the  notch, 
to  the  termination  of  the  fossa  for  the  teres  minor,  the  scapula 
is  narrower  than  any  where  else,  and  supports  the  third  process. 
This  part  has  the  name  of  cervix. 

The  whole  dorsum  of  the  scapula  is  always  said  to  be  con- 
vex ;  but,  by  reason  of  the  raised  edges  that  surround  it,  it  is 


THE    SCAPULA.  179 

divided  into  two  cavities  by  the  spine,  which  is  stretched  from 
behind  forwards,  much  nearer  to  the  superior  than  to  the  inferior 
costa.  The  cavity  above  the  spine  is  really  concave^where 
the  supra-spinatus  muscle  is  lodged  ;  while  the  surface  of  this 
bone  below  the  spine,  on  which  the  infra-spinatus  muscle  is 
placed,  is  convex,  except  a  fossa  that  runs  at  the  side  of 
the  inferior  costa. 

The  internal  or  anterior  surface  of  this  bone  is  hollow,  except 
in  the  part  above  the  spine,  which  is  convex.  The  subscapu- 
laris  muscle  is  extended  over  this  surface,  where  it  forms 
several  ridges  and  intermediate  depressions,  commonly  mis- 
taken for  prints  of  the  ribs  :  they  point  out  the  interstices  of 
the  bundles  of  fibres  of  which  the  subscapularis  muscle  is 
composed. 

The  spine  rises  small  at  the  base  of  the  scapula,  and  becomes 
higher  and  broader  as  it  advances  forwards.  On  the  sides  it  is 
unequally  hollowed  and  crooked,  by  the  action  of  the  adjacent 
muscles.  Its  ridge  is  divided  into  two  rough,  flat  surfaces  :  into 
the  upper  one  the  trapezius  muscle  is  inserted  ;  and  the  lower 
one  has  part  of  the  deltoid  fixed  to  it.  The  end  of  the  spine, 
called  acromion,  or  top  of  the  shoulder,  is  broad  and  flat,  and  is, 
sometimes,  only  joined  to  the  spine  by  a  cartilage.  The  anterior 
edge  of  the  acromion  is  flat,  smooth,  and  covered  with  a  cartilage, 
for  its  articulation  with  the  external  end  of  the  clavicle  ;  and  it  is 
hollowed  below,  to  allow  a  passage  to  the  infra  and  supra-spinati 
muscles,  and  free  motion  to  the  os  humeri. 

The  coracoid  process  is  crooked,  with  its  point  inclining  for- 
wards ;  so  that  a  hollow  is  left  at  the  lower  side  of  its  root  for 
the  passage  of  the  subscapcularis  muscle.  The  end  of  this  pro- 
cess is  marked  with  three  plane  surfaces.  Into  the  internal, 
the  pectoralis  is  inserted  ;  from  the  external,  one  head  of  the 
biceps  flexor  cubiti  rises  ;  and  from  the  lower  one,  the  coraco- 
brachialis  has  its  origin.  At  the  upper  part  of  the  root  of  this 
process,  immediately  before  the  semilunar  cavity,  a  smooth 
tubercle  appears,  where  a  ligament  from  the  clavicle  is  fixed. 
From  the  whole  of  the  external  side  of  this  coracoid  apophysis 


180  THE    SCAPULA. 

a  broad  ligament  goes  out,  which  becomes  narrower  where  it  is 
fixed  to  the  acromion. 

From  the  cervix  scapulae  the  third  process  is  produced. 
The  forepart  of  this  is  formed  into  a  glenoid  cavity,  which  is 
of  the  shape  of  the  longitudinal  section  of  an  egg,  being  broad 
below  and  narrow  above.  Between  the  margin  of  this  cavity 
and  the  forepart  of  the  root  of  the  spine,  a  large  sinuosity  is 
left  for  the  transmission  of  the  supra  and  infra-spinati  muscles ; 
and  on  the  upper  part  of  this  margin  we  may  remark  a  smooth 
surface,  where  the  second  head  of  the  biceps  flexor  cubiti  has 
its  origin.  The  root  of  the  margin  is  rough  all  around,  for  the 
firmer  adhesion  of  the  capsular  ligament  of  the  articulation,  and 
of  the  cartilage  ;  the  latter  is  thick  on  the  margin,  but  becomes 
very  thin  as  it  is  continued  towards  the  middle  of  the  cavity, 
which  it  lines  all  over. 

The  medullary  vessels  enter  the  scapula  near  the  base  of  the 
spine. 

The  substance  of  the  scapula,  as  in  all  other  broad  flat 
bones,  is  cellular,  but  of  an  unequal  thickness :  for  the  neck  and 
third  process  are  thick  and  strong ;  the  inferior  costa,  spine,  and 
coracoid  process,  are  of  a  middle  thickness ;  and  the  body  is  so 
pressed  by  the  muscles,  as  to  become  thin  and  transparent. 

The  scapula  and  clavicle  are  joined  by  plane  surfaces,  tipped 
with  cartilage  ;  by  which  neither  bone  is  allowed  any  consider- 
able motion,  being  tightly  tied  down  by  the  common  capsujar 
ligament,  and  by  a  very  strong  one  which  proceeds  from  the 
coracoid  process ;  but  divides  into  two  before  it  is  fixed  into 
the  clavicle,  with  such  a  direction  as  can  either  allow  this 
bone  to  have  a  small  rotation,  in  which  its  posterior  edge  turns 
more  backwards,  while  the  anterior  one  rises  farther  forwards ; 
or  it  can  yield  to  the  forepart  of  the  scapula  moving  down- 
wards, while  the  back  part  of  it  is  drawn  upwards:  in  both 
which  cases,  the  oblong,  smooth  articulated  surfaces  of  the 
clavicle  and  scapula  are  not  in  the  same  plane,  but  stand  a 
little  transversely,  or  across  each  other,  and  thereby  preserve 
this  joint  from  luxations,  to  which  it  would  be  subject  if  either  of 
A/^*rt^r~ 


THE    OS    HUMERI.  181 

the  bones  were  to  move  on  the  other  perpendicularly  up  and 
down,  without  any  rotation.  Sometimes  a  movable  ligamentous 
cartilage  is  found  in  this  joint ;  and  sometimes  such  a  cartilage 
is  only  interposed  at  the  anterior  half  of  it ;  and  in  some  old 
subjects  a  sesamoid  bone  has  been  found  here. 

The  scapula  is  connected  to  the  head,  os  hyoides,  vertebrae, 
ribSj^and  arm  bone,  by  muscles  that  have  one  end  fastened  to 
these  parts,  and  the  other  to  the  scapula,  which  can  move  it 
upwards,  downwards,  backwards,  or  forwards  :  by  the  quick 
succession  of  these  motions,  its  whole  body  is  carried  in  a 
circle.  But  being  also  often  moved,  as  upon  an  axis  perpen- 
dicular to  its  plane,  its  circumference  turns  in  a  circle  whose 
centre  this  axis  is.  Whichever  of  these  motions  it  performs, 
it  always  carries  the  outer  end  of  the  clavicle  and  the  arm 
along  with  it.  The  glenoid  cavity  of  this  bone  receives  the  os 
humeri,  which  plays  in  it,  as  will  be  more  fully  explained  here- 
afterT 

The  use  of  the  scapula,  is,  to  serve  as  a  fulcrum  to  the  arm ; 
and  by  altering  its  position  on  different  occasions,  to  allow  always 
to  the  head  of  the  os  humeri  a  socket  to  move  in  properly 
situated ;  and  thereby  to  assist  and  to  enlarge  greatly  the  motions 
of  the  superior  extremity,  and  to  afford  the  muscles  which  rise 
from  it  more  advantageous  actions,  by  altering  their  directions 
with  respect  to  the  bone  which  they  are  to  move.  This  bone 
also  serves  to  defend  the  back  part  of  the  thorax,  and  is  often 
employed  to  sustain  weights,  or  to  resist  forces  too  great  for  the 
arm  to  bear. 


Os  Humeri,  or  Arm  Bone.  » 

The  arm  has  only  one  bone,  best  known  by  the  Latin  name 
of  os  humeri ;  which  is  long,  round,  and  nearly  straight. 

The  upper  end  of  this  bone  consists  of '  a  large  round 
smooth  head,  which  forms  the  segment  of  a  sphere,  whose 
axis  is  not  in  a  straight  line  with  the  axis  of  the  bone,  but 
stands  obliquely  backwards  from  it.  The  extent  of  the  head 
is  distinguished  by  a  circular  fossa  surrounding  its  base,  where 
16 


182 


THE    OS    HUMERI. 


Fig.  41.*  the  head  is  united  to  the  bone,  and  the  capsular 
ligament  of  the  joint  is  fixed.  Below  the  fore- 
part of  its  base,  two  tubercles  stand  out :  the 
smaller  one,  which  is  situated  most  to  the  inside, 
has  the  tendon  of  the  subscapularis  muscle  in- 
serted into  it.  The  larger  more  external  pro- 
tuberance is  divided,  at  its  upper  part,  into 
three  smooth  plane  surfaces :  into  the  anterior 
of  which,  the  musculus  supra-spinatus ;  into 
the  middle  or  largest,  the  infra-spinatus  ;  and 
into  the  one  behind,  the  teres  minor,  is  inserted. 
Between  these  two  tubercles,  exactly  in  the 
forepart  of  the  bone,  a  deep  long  groove  is 
formed,  for  lodging  the  tendinous  head  of  the 
biceps  flexor  cubiti ;  which,  after  passing,  in  a 
manner  peculiar  to  itself,  through  the  cavity  of 
the  articulation,  is  tied  down,  by  a  tendinous 
sheath  extended  across  the  groove  ;  in  which, 
and  in  the  neighboring  tubercles,  are  several 
remarkable  holes,  which  are  penetrated  by  the  tendinous  and 
ligamentous  fibres,  and  by  vessels.  On  each  side  of  this 
groove,  as  it  descends  in  the  os  humeri,  a  rough  ridge,  gently 
flattened  in  the  middle,  runs  from  the  roots  of  the  tubercles. 
The  tendon  of  the  pectoral  muscle  is  fixed  into  the  anterior  of 
these  ridges,  and  the  latissimus  dorsi  and  teres  major  are 
inserted  into  the  internal  one.  A  little  behind  the  lower  end 
of  this  last,  another  rough  ridge  may  be  observed,  where  the 
coraco-brachialis  is  inserted.  From  the  back  part  of  the  root 
of  the  largest  tubercle,  a  ridge  also  is  continued;  from  which 
the  extensor  brevis  cubiti  arises.  This  bone  is  flattened  on  the 


*  The  humerus  of  the  right  side ;  its  anterior  surface.  1.  The  shaft  of  the 
bone.  2.  The  head.  3.  The  anatomical  neck.  4.  The  greater  tuberosity.  5. 
The  lesser  tuberosity.  6.  The  bicipital  groove.  7.  The  anterior  bicipital  ridge. 
8.  The  posterior  bicipital  ridge.  9.  The  rough  surface  into  which  the  deltoid  is 
inserted.  10.  The  nutritious  foramen.  11.  The  rounded  protuberance  of  the 
articular  surface.  12.  The  pulley-like  surface.  13.  The  external  condyle.  14. 
The  internal  condyle.  15.  The  external  conclyloid  ridge.  16.  The  internal 
condyloid  ridge.  17.  The  fossa  for  the  coronoid  process  of  the  ulna. 


THE    OS    HUMERI.  183 

inside,  about  its  middle,  by  the  belly  of  the  biceps  flexor  cubiti. 
In  the  middle  of  this  plane  surface,  the  entry  of  the  medullary 
artery  is  seen  slanting  obliquely  downwards.  At  the  fireside 
of  this  plane,  the  bone  rises  in  a  sort  of  ridge,  which  is  rough, 
and  often  has  a  great  many  small  holes  in  it,  where  the  strong 
deltoid  muscle  is  inserted  ;  on  each  side  of  which  the  bone  is 
smooth  and  flat,  where  the  brachialis  internus  rises.  The 
exterior  of  these  two  flat  surfaces  is  the  largest :  behind  it  is  a 
superficial  spiral  channel,  formed  by  the  muscular  nerve,  and  the 
vessels  that  accompany  it ;  it  runs  from  behind  forwards  and 
downwards. 

The  body  of  the  os  humeri  is  flattened  behind  by  the  exten- 
sors of  the  forearm. 

Near  the  lower  end  of  this  bone,  a  large  sharp  ridge  is 
extended  on  its  outside  ;  from  which  the  musculus  supinator 
radii  longus,  and  the  longest  head  of  the  extensor  carpi  radi- 
alis,  arise.  Opposite  to  this  there  is  another  small  ridge  to 
which  the  aponeurotic  tendon,  that  gives  origin  to  the  fibres  of 
the  internal  and  external  brachial  muscles,  is  fixed  ;  and  from 
a  little  depression  on  the  foreside  of  it,  the  pronator  radii  teres 
arises. 

The  body  of  the  os  humeri  becomes  gradually  broader 
towards  the  lower  end,  where  it  has  several  processes  ;  at  the 
roots  of  which  there  is  a  cavity  before,  and  one  behind,  called 
sigmoid.  The  anterior  is  divide'd  by  a  ridge  into  two  ;  the 
external,  which  is  the  least,  receives  the  end  of  the  radius  ;  and 
the  internal  receives  the  coronoid  process  of  the  ulna,  in  the 
flexions  of  the  forearm  ;  while  the  posterior  deep  triangular 
cavity  lodges  the  olecranon  in  the  extensions  of  that  limb. 
The  bone  between  these  two  cavities  is  pressed  so  thin  by  the 
processes  of  the  ulna,  as  to  appear  transparent  in  many  sub- 
jects. The  sides  of  the  posterior  cavity  are  stretched  out  into 
two  processes,  one  on  each  side.  These  are  called  condyles ; 
from  each  of  which  a  strong  ligament  goes  out  to  the  bones  of 
the  forearm.  The  external  condyle,  which  has  an  oblique 
direction  forwards  with  respect  to  the  internal,  when  the  arm 


184  THE    OS    HUMERt. 

is  in  the  most  natural  posture,  is  equally  broad,  and  has  an 
obtuse  smooth  head  rising  from  it  forwards.  From  the  rough 
part  of  the  condyle,  several  muscles  arise  ;  and  on  the  smooth 
head  the  upper  end  of  the  radius  plays.  The  internal  condyle 
is  more  pointed  and  protuberant  than  the  external,  to  give  origin 
to  the  flexor  muscles  of  the  wrist  and  hands,  &c.  Between 
the  two  condyles,  is  the  trochle^i,  or  pulley  ;  which  consists  of 
two  lateral  protuberances  and  a  middle  cavity  that  are  smooth, 
and  covered  with  cartilage.  When  the  forearm  is  extended,  the 
tendon  of  the  internal  brachialis  muscle  is  lodged  in  the  forepart 
of  the  cavity  of  this  pulley.  The  external  protuberance,  which 
is  less  than  the  other,  has  a  sharp  edge  behind  :  but  forwards, 
this  ridge  is  obtuse,  and  only  separated  from  the  little  head, 
already  described,  by  a  small  fossa,  in  which  the  adjoining  edges 
of  the  ulna  and  radius  move.  The  internal  protuberance  of  the 
pulley  is  largest  and  highest ;  and  therefore,  in  the  motions  of 
the  ulna  upon  it,  that  bone  would  be  inclined  outwards,  were 
it  not  supported  by  the  radius  on  that  side.  Between  this  in- 
ternal protuberance  and  condyle,  a  sinuosity  may  be  remarked, 
where  the  ulnar  nerve  passes. 

The  substance  and  the  internal  structure  of  the  os  humeri 
are  the  same,  and  disposed  in  the  same  way,  as  in  the  other  long 
bones. 

The  round  head,  at  the  upper  end  of  this  bone,  is  articulated 
with  the  glenoid  cavity  of  the  scapula  ;  which  being  superficial 
and  having  long  ligaments,  allows  the  arm  a  free  and  extensive 
motion.  These  ligaments  are,  however,  considerably  strong. 
For,  besides  the  common  capsular  ligament,  the  tendons  of  the 
muscles  perform  the  office,  and  have  been  described  under  the 
name  of  ligaments.  Then  the  acromion  and  coracoid  process,* 
with  the  strong  broad  ligaments  stretched  between  them,  secure 
the  articulation  above  ;  where  the  greatest  and  most  frequent 
force  is  applied,  to  thrust  the  head  of  the  bone  out  of  its  place. 
It  is  true,  that  there  is  not  near  so  strong  a  defence  in  the  lower 
part  of  the  articulation  ;  but,  in  the  ordinary  postures  of  the 
arm,  that  is,  so  long  as  it  is  an  acute  angle  with  the  trunk  of 


BONES   OF  THE  FOREARM.  185 

the  body,  there  cannot  be  any  force  applied  at  this  place  to 
occasion  a  luxation,  since  the  joint  is  protected  so  well 
above. 

The  motions  which  the  arm  enjoys  by  this  articulation,  are 
to  every  side ;  and,  by  the  succession  of  these  different  motions, 
a  circle  may  be  described.  Besides  which,  the  bone  performs 
a  small  rotation  round  its  own  axis ;  but,  when  the  axis  of  the 
bone  is  the  centre  of  motion,  the  movements  are  very  different 
from  those  which  take  place  when  the  axis  of  its  head  is  the 
centre;  for  the  axis  of  the  head  forms  a  very  large  angle  with 
the  axis  of  the  body  of  the  bone.  Thus,  when  the  arm  swings 
backwards  and  forwards,  the  axis  of  the  head  is  the  centre  of 
motion  :  but  when  the  elbow  is  bent,  and  the  forearm  forms  a 
right  angle  with  the  os  humeri,  the  motion  which  applies  the 
forearm  to  the  thorax,  or  removes  it,  is  a  rotation  of  this  bone 
on  its  axis. 

Though  the  motions  of  the  arm  seem  to  be  very  extensive, 
yet  the  larger  share  of  them  depends  on  the  motions  of  the 
scapula ;  for  the  surface  of  the  glenoid  cavity  is  directed 
upwards  or  downwards,  and,  to  a  certain  degree,  backwards 
or  forwards,  to  support  the  head  of  the  os  humeri.  This  is 
exemplified  when  we  press  the  hand  against  a  body  which  is 
before,  or  above,  or  to  one  side  of  us. 

The  lower  end  of  the  os  humeri  is  articulated  to  the  bones  of 
the  forearm,  and  carries  them  with  it  in  all  its  motions ;  but 
serves  as  a  base,  on  which  they  perform  the  motions  peculiar  to 
themselves;  as  will  shortly  be  described. 

The  Forearm 

Consists  of  two  bones,  one  of  which  is  called  ulna,  from  its 
being  used  as  a  measure ;  and  the  other  radius,  from  the  sup- 
posed resemblance  to  the  spoke  of  a  wheel.  ,, 

These  bones  are  concerned  in  very  different  operations.     The 
ulna  forms  the  elbow  joint  with  the  os  humeri ;  the  radius  is 
the  movable  basis  of  the  hand. 
16* 


186  THE    ULNA. 

Vina. 

The  length  of  this  bone  is  equal  to  the  forearm,  of  which 
it  is  a  part.  It  is  thickest  above,  and  gradually  diminishes 
until  near  its  lower  end.  The  body  of  the  bone  is  nearly 
Fig.  42.*  triangular  in  form.  At  the  upper  extremity 
of  the  ulna,  on  its  anterior  surface,  is  a 
semicircular  notch.  The  end  of  the  bone 
which  forms  the  posterior  part  of  this 
notch  is  denominated  olecranon.  The  an- 
terior part  of  the  notch  is  formed  by  a 
process  called  coronoid.  This  notch  ap- 
plies to  the  pulley-like  surface  on  the  internal 
side  of  the  lower  extremity  of  the  os  humeri, 
to  form  the  articulation  of  the  elbow.  In 
the  middle  of  the  concave  surface  is  a  ridge, 
in  consequence  of  which,  a  srqall  rocking 
motion  is  performed  by  the  ulna.  The 
external  surface  of  the  olecranon  is  rough, 
and  strongly  marked.  The  extensor  mus- 
cle of  the  forearm  is  inserted  into  the 
end  of  it,  and  below  this  is  a  flat  surface 
on  which  we  lean.  On  the  outside  of 
the  coronoid  process  is  a  semilunated  smooth  cavity,  lined 
with  cartilage;  in  which,  and  in  a  ligament  extended 
from  the  one  to  the  other  end  of  this  cavity,  the  round 
head  of  the  radius  plays.  Immediately  below  it,  a  rough 
hollow  gives  lodging  to  the  mucilaginous  glands.  Below  the 
root  of  the  coronoid  process,  this  bone  is  scabrous  and  unequal, 
where  the  brachialis  interims  is  inserted.  On  the  outside  of 


*  The  two  bones  of  the  forearm  seen  from  the  front.  1.  The  shaft  of  the  ulna. 
2.  The  greater  sigmoid  notch.  3.  The  lesser  sigmoid  notch,  with  which  the 
head  of  the  radius  is  articulated.  4.  The  olecranon  process.  5.  The  coronoid 
process.  6.  The  nutritious  foramen.  7.  The  sharp  ridges  upon  the  two  bones 
to  which  the  interosseous  membrane  is  attached.  8.  The  rounded  head  at  the 
lower  extremity  of  the  ulna.V9.  The  styloid  process.  10.  The  shaft  of  the 
radius.  11.  Its  head  surrounded  by  the  smooth  border  for  articulation  with  the 
orbicular  ligament.  12.  The  neck  of  the  radius.  13.  Its  tuberosity.  14.  The 
oblique  line.  15.  The  lower  extremity  of  the  bone.  16.  Its  styloid  process. 


THE    ULNA.  187 

that,  we  observe  a  smooth  concavity,  where  the  beginning  of 
the  flexor  digitorum  profundus  sprouts  out. 

The  external  angle  of  the  triangular  part  of  the  ulnajs  very- 
sharp,  where  the  ligament  that  connects  the  two  bones  is  fixed  ; 
the  sides  which  make  this  angle  are  flat  and  rough,  by  the  ac- 
tion and  adhesion  of  the  many  muscles  which  are  situated 
here.  At  the  distance  of  one-third  of  the  length  of  the  ulna 
from  the  top,  in  its  forepart,  the  passage  of  the  medullary  ves- 
sels may  be  seen  slanting  upwards.  The  internal  side  of  the 
bone  is  smooth,  somewhat  convex,  and  the  angles  at  each  edge 
of  it  are  blunted  by  the  pressure  of  the  muscles  equally  disposed 
about  them.  ' 

As  this  bone  descends,  it  becomes  gradually  smaller ;  so  that 
its  lower  end  terminates  in  a  little  head,  standing  on  a  small 
neck  :  towards  the  inner  and  back  part  of  which  last,  an  oblique 
ridge  runs,  that  gives  rise  to  the  pronator  radii  quadratus.  The 
head  is  sometimes  cylindrical,  smooth,  and  covered  with  a  car- 
tilage on  its  external  side,  to  be  received  into  the  semilunar 
cavity  of  the  radius ;  which  a  styloid  process  rises  from  its  in- 
side, to  which  is  fixed  a  strong  ligament  that  is  extended  to  the 
os  cuneiforme  and  pisiforme  of  the  wrist.  At  the  root  of  the 
process,  the  end  of  the  bone  is  smooth,  and  covered  with  a  car- 
tilage. Between  it  and  the  bones  of  the  wrist,  a  doubly  con- 
cave movable  cartilage  is  interposed ;  which  is  a  continuation 
of  the  cartilage  that  covers  the  lower  end  of  the  radius,  and  is 
connected  loosely  to  the  root  of  the  styloid  process,  and  to  the 
rough  cavity  there ;  in  which  mucilaginous  glands*  are 
lodged. 

The  ulna  is  principally  concerned  in  the  articulation  with  the 
os  humeri,  and  forms  a  hinge-like  joint,  which  allows  extension 
nearly  to  a  straight  line,  and  flexion  to  an  acute  angle.  By  the 
sloping  of  the  pulley-like  surface,  the  lower  part  of  the  arm  is 
turned  outwards  in  the  extension,  and  inwards  in  the  flexion ; 
which  greatly  facilitates  the  motion  of  the  hand  towards  the 
head. 

*  All  these  so  called  glands  are  m.ere  masses  of  adipose  matter,  supposed, 
though  wrongly  by  Havers  to  be  the  glands  which  secrete  the  synovia. — P. 


188  RADIUS. 

Radius. 

Before  the  radius  is  described,  it  is  necessary  to  observe  that  the  lower  end  of 
this  bone  occasionally  revolves  half  round  the  lower  end  of  the  ulna,  and  the 
hand  with  it.  The  relative  situation  of  these  parts  is,  therefore,  different  in 
different  positions  of  the  hand.  In  the  following  description,  the  palm  of  the 
hand  is  supposed  to  present  forwards,  and  the  thumb  outwards  j  in  which  case, 
the  two  bones  of  the  forearm  will  be  parallel  to  each  other. 

• 
The  radius  is  situated  on  the  outside  of  the   forearm,  and  is 

rather  shorter  than  the  ulna.  Its  extremities  are  the  reverse  of 
those  of  the  ulna  in  their  proportionate  size  ;  and  the  body  is 
not  triangular,  although  it  approaches  towards  that  form.  Its 
upper  end  is  formed  into  a  cylindrical  head,  which  is  hollowed 
on  the  top  for  an  articulation  with  the  tubercle  at  the  side  of 
the  pulley  of  the  os  hurneri ;  and  the  half  cylindrical  circum- 
ference next  to  the  ulna  is  smooth,  and  covered  with  a  carti- 
lage, in  order  to  be  received  into  the  sernilunated  cavity  of  that 
bone.  Below  the  head,  the  radius  is  much  smaller ;  and,  there- 
fore, this  part  is  named  its  cervix. >(  At  the  internal  root  of  this 
neck  is  a  flat  tubercle,  into  the  inner  part  of  which  the  biceps 
flexor  cubiti  is  inserted.  From  this  a  ridge  runs  downwards  and 
outwards  where  thesupinator  radii  brevis  is  inserted;  and  a  little 
below,  and  behind  this  ridge,  there  is  a  rough  scabrous  surface, 
where  the  pronator  radii  teres  is  fixed. 

The  body  of  the  radius  is  not  straight,  but  curved  externally 
the  greater  part  of  its  length.  Its  external  surface  is  rounded  ; 
tne  anterior  and  posterior  surfaces  are  flattened ;  and  between 
them  is  a  sharp  spine,  to  which  the  strong  ligament  extended 
between  the  two  bones  of  the  forearm  is  fixed.  On  the  ante- 
rior surface,  at  a  distance  from  its  head,  nearly  equal  to  one- 
third  the  length  of  the  bone,  is  the  orifice  of  the  canal  for 
the  medullary  vessels,  which  has  a  direction  obliquely  up- 
wards. 

Towards  the  lower  end  the  radius  becomes  broader  and 
flatter,  especially  on  its  forepart,  where  the  pronator  quadratus 
muscle  is  situated.  Its  back  part,  at  this  end,  has  a  flat  strong 
ridge  in  the  middle,  and  fossae  on  each  side.  In  a  small  groove, 

'     • 


RADIUS.  189 

immediately  on  the  inside  of  the  ridge,  the  tendon  of  the 
extensor  of  the  last  joint  of  the  thumb  plays.  In  a  large  one, 
inside  of  this,  the  tendons  of  the  indicator,  and  of  the  common 
extensor  muscles  of  the  fingers  pass.  On  the  outside  *6f  the 
ridge  there  is  a  broad  depression,  which  seems  again  subdivided, 
where  the  two  tendons  of  the  extensor  carpi  radialis  are  lodged. 
The  external  side  of  this  end  of  the  radius  is  also  hollowed 
by  the  extensors  of  the  first  and  second  joints  of  the  thumb. 
The  ridges  at  the  sides  of  the  grooves,  in  which  the  ten- 
dons play,  have  an  annular  ligament  fixed  to  them,  by  which 
the  several  sheaths  for  the  tendons  are  formed.  The  forepart 
of  this  end  of  the  radius  is  also  depressed,  where  the  flexors  of 
the  fingers  and  flexor  carpi  radialis  pass.  The  internal  side  is 
formed  into  a  semilunated  smooth  cavity,  lined  with  a  cartilage, 
for  receiving  the  lower  end  of  the  ulna.  The  lowest  part  of 
the  radius  is  formed  into  an  oblong  cavity  ;  in  the  middle  of 
which  is  a  small  transverse  rising,  gently  hollowed,  for  lodging 
mucilaginous  glands ;  while  the  rising  itself  is  insinuated  into 
the  conjunction  of  the  two  bones  of  the  wrist  that  are  received 
into  the  cavity.  The  external  side  of  this  articulation  is  defended 
by  a  remarkable  process  of  the  radius,  from  which  a  ligament 
passes  to  the  wrist ;  and  this  structure  resembles  that  of  the 
styloid  process  of  the  ulna  with  its  ligament. 

The  ends  of  both  the- bones  of  the  forearm  being  thicker  than 
the  middle,  and  the  radius  being  curved,  there  is  a  considerable 
distance  between  the  bodies  of  these  bones ;  in  the  larger  part  of 
which  a  strong,  tendinous,  but  tliin  ligament,  is  extended,  to  give 
a  sufficient  surface  for  the  origin  of  the  numerous  fibres  of  the 
muscles  situated  here,  that  are  so  much  sunk  between  the  bones 
as  to  be  protected  from  injuries,  to  which  they  would  otherwise 
be  exposed.  But  this  ligament  is  wanting  near  the  upper  end  ~ 
of  the  forearm,  where  the  supinator  radii  brevis  and  flexor  digi- 
torum  profundus,  are  immediately  connected. 

As  the  head  of  the  radius  receives  the  tubercle  of  the  os 
humeri,  it  is  not  only  bended  and  extended  along  with  the  ulna, 
but  may  be  moved  almost  half  round  its  axis ;  and  that  this 


190  THE    HAND. 

motion  round  its  axis  may  be  sufficiently  large,  the  ligament 
of  the  articulation  is  extended  farther  down  than  ordinary,  on 
the  neck  of  this  bone,  before  it  is  connected  to  it  ;  and  it  is 
very  thin  at  its  upper  and  lower  part,  but  makes  a  firm  ring  in 
the  middle.  This  bone  is  also  joined  to  the  ulna  by  a  double 
articulation  :  for  above,  a  tubercle  of  the  radius  plays  in  a  socket 
of  the  ulna ;  whilst  below,  the  radius  gives  the  socket,  and  the 
ulna  the  tubercle.  But  then  the  motion  performed  at  the  two 
ends  is  very  different :  for,  at  the  upper  end,  the  radius  does  little 
more  than  turn  round  its  axis ;  while,  at  the  lower  end,  it  moves 
nearly  half  round  the  cylindrical  end  of  the  ulna ;  and,  as  the 
hand  is  articulated  and  firmly  connected  here  with  the  radius, 
they  must  move  together.  When  the  palm  is  turned  uppermost, 
the  radius  is  said  to  perform  supination :  when  the  back  of  the 
hand  is  above,  it  is  said  to  be  prone.  But  then  the  quickness 
and  large  extent  of  these  two  motions  are  assisted  by  the  ulna, 
which,  as  was  before  observed,  can  move  wilh  a  kind  of  small 
rotation  on  the  sloping  sides  of  the  pulley.  This  rocking  motion, 
though  very  inconsiderable  in  the  elbow  joint  itself,  is  conspicu- 
ous at  the  lower  end  of  such  a  long  bone ;  and  the  strong 
ligament  connecting  this  lower  end  to  the  carpus,  makes  the 
hand  more  readily  obey  these  motions. 

The  Hand. 

The  hand  comprehends  the  whole  structure,  from  the  end  of 
the  radius  to  the  points  of  the  fingers.  Its  back  part  is  convex, 
for  greater  firmness  and  strength  ;  and  it  is  concave  before,  for 
containing  more  surely  and  conveniently  such  bodies  as  we 
take  hold  of.  One  half  of  the  hand  has  an  obscure  motion  in 
comparison  of  what  the  other  has  ;  it  serves  as  a  base  to  the 
movable  half,  which  can  be  extended  back  very  little  farther  than 
to  a  straight  line  with  the  forearm,  but  can  be  considerably  bent 
forwards. 

The  hand  consists  of  the  carpus  or  wrist ;  metacarpus,  or 
part  adjoining  the  wrist ;  and  the  fingers,  a*mong  which  the 
thumb  is  reckoned. 


CARPUS.  191 

Carpus. 

No  part  of  the  skeleton  is  more  complex  than  the  carpus.  The  following  descrip- 
tion will,  therefore,  be  of  little  use  to  a  young  student,  unless  the  bones  are 
before  him  when  he  is  reading  it.  Great  advantage  will  be  derived  from 
examining  two  sets  of  carpal  bones:  each  set  belonging  to  the  same  side. 
In  one  of  these  sets  the  bones  should  be  connected  by  their  natural  ligaments  ; 
but  the  two  rows  separated  from  each  other.  The  bones  of  the  other  set 
should  be  accurately  cleaned;  so  that  their  forms  and  surfaces  may  be  examined. 

The  carpus  is  composed  of  eight  small  bones,  arranged  in  two 
rows  ;  one  of  which  rows  is  attached  to  the  bones  of  the  fore- 
arm, and  the  other  to  the  body  of  the  hand.  <@ 

These  bones  are  named  from  their  figure  and  shall  be 
mentioned  in  the  order  in  which  they  occur,  beginning  with  the 
row  next  to  the  forearm ;  and  with  the  external  bone  in  each 
row. 

They  are,  Os  Scaphoides,  Lunare,  Cuneiforme,  Pisiforme, 
forming  the  upper  row  ;  Os  Trapezium,  Trapezoides,  Magnum, 
and  Unciforme,  forming  the  lower  row. 

First  Row. 

Os  scaphoides  is  the  largest  of  the  eight,  excepting  one.  It 
is  convex  above,  concave  and  oblong  below  ;  from  which  small 
resemblance  to  a  boat,  it  has  got  its  name.  Its  smooth  convex 
surface  is  divided  by  a  rough  middle  fossa,  which  runs  obliquely 
across  it.  The  upper  largest  division  is  articulated  with  the 
radius.  The  common  ligament  of  the  joint  of  the  wrist  is  fixed 
into  the  fossa  ;  and  the  lower  division  is  joined  to  the  trapezium 
and  trapezoides.  The  concavity  receives  more  than  half  of  the 
round  head  of  the  os  magnum.  The  internal  side  of  this  hollow 
is  formed  into  a  semilunar  plane  to  be  articulated  with  the 
following  bone.  The  external,  posterior,  and  anterior  edges  are 
rough,  for  fixing  the  ligaments  that  connect  it  to  the  surrounding 
bones. 

Os  lunare  has  a  smooth  convex  upper  surface,  by  which  it  is 
articulated  with  the  radius.  The  external  side,  which  gives 
the  name  to  the  bone,  is  in  the  form  of  a  crescent,  nad  is 
joined  with  the  scaphoid  :  the  lower  surface  is  hollow,  for 
receiving  part  of  the  head  of  the  os  magnum.  On  the  inside 


192 


CARPUS. 


Fig.  43.*  of     this    cavity    is    another   smooth, 

but  narrow,  oblong  sinuosity,  for 
receiving  the  upper  end  of  the 
unciforme :  and  on  the  inside  of  this 
a  small  convexity  is  found,  for  its 
connexion  with  the  os  cuneiforme. 
Between  the  great  convexity  above, 
and  *  the  first  deep  inferior  cavity, 
there  is  a  rough  fossa,  in  which  the 
circular  ligament  of  the  joint  of  the 
wrist  is  fixed. 

Os  cuneiforme  is  broader  above 
and  towards  the  back  of  the  hand, 
than  it  is  below  and  forwards ;  which  gives  it  the  resem- 
blance of  a  wedge.  The  superior  slightly  convex  surface  is 
included  in  the  joint  of  the  wrist,  being  opposed  to  the  lower 
end  of  the  ulna.  Below  this  the  cuneiforme  bone  has  a  rough 
fossa,  wherein  the  ligament  of  the  articulation  of  the  wrist  is 
fixed.  On  the  external  side  of  this  bone,  where  it  is  contiguous 
to  the  os  lunare,  it  is  smooth,  and  slightly  concave.  Its  lower 
surface,  where"  it  is  contiguous  to  the  os  unciforme,  is  oblong, 
somewhat  spiral,  and  concave.  Near  the  middle  of  its  anterior 
surface,  a  circular  plane  appears,  where  the  os  pisiforme  is 
sustained. 

Os  pisiforme  is  almost  spherical,  except  one  circular  plane, 
or  slightly  hollowed  surface,  which  is  covered  with  cartilage  for 
its  motion  on  the  cuneiforme  bone,  from  which  its  whole 


*  A  diagram  showing  the  dorsal  surface  of  the  bones  of  the  carpus,  with 
their  articulations. — The  right  hand.  R.  The  lower  end  of  the  radius.  U.  The 
lower  extremity  of  the  ulna.  F.  The  inter-articular  fibro- cartilage  attached  to 
the  styloid  process  of  the  ulna,  and  to  the  margin  of  the  articular  surface  of  the 
radius.  S.  The  scaphoid  bone :  the  numeral  (5)  indicates  the  number  of  bones 
with  which  it  articulates.  L.  The  semilunare  articulating  with  five  bones.  C. 
The  cuneiforme,  articulating  with  three  bones.  P.  The  pisiforme,  articulating 
with  the  cuneiforme  only.  T.  The  first  bone  of  the  second  row — the  trapezium, 
articulating  with  four  bones.  T.  The  second  bone — the  trapezoides,  articulating 
also  with  four  bones.  M.  The  os  magnum,  articulating  with  seven.  U.  The 
unciforme,  articulating  with  five.  The  numerals,  1, 3,  1,2, 1,  on  the  metacarpal 
bones,  refer  to  the  number  of  their  articulations  with  the  carpal  bones. 


CARPUS.  193 

rough  body  is  prominent  forwards  into  the  palm ;  having  the 
tendon  of  the  flexor  carpi  ulnaris,  and  a  ligament  from  the 
styloid  process  of  the  ulna  fixed  to  its  tipper  part ;  the  trans- 
verse ligament  of  the  wrist  is  connected  to  its  externaFside  : 
ligaments  extended  to  the  unciforme  bone,  and  to  the  os 
metacarpi  of  the  little  finger,  are  attached  to  its  lower  part ; 
the  abductor  minimi  digiti  has  its  origin  from  its  forepart ; 
and,  at  the  external  side  of  it,  a  small  depression  is  formed  for 
the  psssage  of  the  ulnar  nerve. 

Second  Row. 

Os  Trapezium  has  four  unequal  sides  and  angles  in  its  back 
part,  from  which  it  has  got  its  name.  Above,  its  surface  is 
smooth,  slightly  hollowed,  and  semicircular,  for  its  conjunction 
with  the  os  scaphoides.  Its  internal  side  is  an  oblong  concave 
square,  for  receiving  the  following  bone.  The  inferior  surface 
is  formed  into  a  pulley,  which  faces  obliquely  outwards  and 
downwards  when  the  palm  presents  forward.  On  this  pulley 
the  first  bone  of , the  thumb  is  moved. 

At  the  internal  side  of  the  pulley,  a  small  oblong  smooth 
surface  is  formed  by  the  os  metacarpi  indicis.  The  forepart 
of  the  trapezium  is  prominent  in  the  palm,  and  near  to  the  in- 
ternal side  has  a  sinuosity  in  it,  where  the  tendon  of  the  flexor 
carpi  radialis  is  lodged,  on  the  ligamentous  sheath  of  which 
the  tendon  of  the  flexor  longus  pollicis  manus  plays :  near 
this  the  bone  is  scabrous,  where  the  transverse  ligament  of 
the  wrist  is  connected,  the  abductor  and  the  flexor  brevis 
pollicis  have  their  origin,  and  ligaments  go  out  to  the  first  of 
the  thumb. 

Os  trapezoides,  so  called  from  the  irregular  quadrangular 
figure  of  its  back  part,  is  the  smallest  bone  of  the  wrist,  except 
the  pisiforme.  The  figure  of  it  is  an  irregular  cube.  It  has  a 
small  hollow  surface  above,  by  which  it  joins  the  scaphoides ; 
a  long  convex  one  externally,  where  it  is  contiguous  to  the 
trapezium ;  a  small  internal  concavity,  for  its  conjunction 
with  the  os  magnum ;  and  an  inferior  convex  surface,  the 
edges  of  which  are,  however,  so  raised  before  and  behind,  that 
17 


194  CARPUS. 

a  sort  of  pulley  is   formed,  where  it  sustains  the  os  metacarpi 
indicis. 

Os  magnum,  so  called  because  it  is  the  largest  bone  of  the 
carpus,  is  oblong,  having  four  quadrangular  sides,  with  a  round 
upper  end,  and  a  triangular  plane  one  below.  The  round  head 
is  divided  by  a  small  rising,  opposite  to  the  connexion  of  the 
os  scaphoides  and  lunare,  which  together  form  the  cavity  for 
receiving  it.  On  the  outside  a  short  plane  surface  joins  the  os 
magnum  to  the  trapezoides.  On  the  inside  is  a  long  narrow 
concave  surface  where  it  is  contiguous  to  the  os  unciforme. 
The  lower  end,  which  sustains  the  metacarpal  bone  of  the 
middle  finger,  is  triangular,  slightly  hollowed,  and  farther 
advanced  on  the  external  side  than  on  the  internal,  having  a 
considerable  oblong  depression  made  on  the  advanced  outside 
by  the  metacarpal  bone  of  the  fore-finger ;  and  generally  there 
is  a  small  mark  of  the  os  metacarpi  digiti  annularis  on  its  inter- 
nal side. 

Os  unciforme  has  got  its  name  from  a  thin  broad  process 
that  stands  out  from  it  forwards  into  the  palr%  and  is  hollow, 
for  affording  passage  to  the  tendons  of  the  flexors  of  the  fingers. 
To  this  process,  also,  the  transverse  ligament  is  fixed  that  binds 
down,  and  defends  these  tendons ;  and.  the  flexor  and  abductor 
muscles  of  the  little  finger  have  part  of  their  origin  from  it. 
The  upper  plane  surface  is  small,  convex,  and  joined  with 
the  os  lunare :  the  external  side  is  long  and  slightly  convex, 
adapted  to  the  contiguous  os  magnum.  The  internal  surface  is 
oblique,  and  irregularly  convex,  to  be  articulated  with  the 
cuneiforme  bone.  The  lower  end  is  divided  into  two  concave 
surfaces;  the  internal  is  joined  with  the  metacarpal  bone  of 
the  little  finger;  and  the  external  one  is  fitted  to  the  metacarpal 
bone  of  the  ring  finger. 

The  nature  of  the  carpus  will  be  best  understood  by  studying 
the  bones  placed  together,  in  their  natural  order,  in  the  two 
rows. 

When  thus  placed,  they  compose  a  structure  of  an  oblong 
form,  whose  greatest  length  extends  across  the  wrist,  and  forms 
a  concavity  in  front,  while  it  is  convex  posteriorly. 


CARPUS. 


195 


Fig.  44.*  Two  bones  of  the  first  row,  viz.,  the 

scaphoides  and  lunare,  form  an  oblong 
convex  surface,  which  has  a  transverse 
position  with  respect  to  the  arm,  and 
applies  to  the  concave  surface  at  the 
end  of  the  radius.  These  surfaces  are 
particularly  calculated  for  flexion  and 
extension,  and  also  for  a  considerable 
motion  to  each  side ;  and  by  a  suc- 
cession of  these  flexures,  in  different 
directions,  the  hand  performs  a  cir- 
cular motion,  although  it  cannot 
perform  at  this  joint  a  rotation,  or 
revolution,  on  the  axis  of  the  car- 
pus. 

The  under  surface  of  the  bones  has  a  deep  concavity,  which 
is  composed  by  the  scaphoides,  lunare  and  cuneiforme,  and 
receives  a  prominence  of  the  second  row.  It  also  presents  a 
convex  surface,  formed  by  the  scaphoides,  which  is  received 
by  the  second  row. 

The  upper  surface  of  the  second  row,  which  is  concerned  in 
this  articulation,  is  very  irregular ;  it  has  a  head  formed  by  the 
magnum  and  unciforme,  which  penetrates  deeply  into  the 
cavity  of  the  first  row.  On  the  outside  of  this  head  the  tra- 
pezium and  trapezoides  form  a  surface,  which  receives  the 
projecting  part  of  the  scaphoides ;  so  that  the  first  row  receives, 
and  is  received  by  the  second,  and  the  two  surfaces  are  well 
calculated  for  moving,  to  a  certain  extent,  in  the  way  of  flexion 
and  extension,  upon  each  other.  I 

The  lower  surface  of  the  second  row,  which  is  connected  to 

*  The  hand  viewed  upon  its  anterior  or  palmer  aspect.  1.  The  scaphoid  bone. 
2.  The  semilunare.  3.  The  cuneiforme.  4.  The  pisiforme.  5.  The  trapezium. 
6.  The  groove  in  the  trapezium  that  lodges  the  tendon  of  the  flexor  carpi 
radialis.  7.  The  trapezoides.  8.  The  os  magnum.  9.  The  unciforme.  10,  10. 
The  five  metacarpal  bones.  11,  11.  The  first  row  of  phalanges.  12,  12.  The 
second  row.  13,  13.  The  third  row,  or  ungual  phalanges.  14.  The  first  phalanx 
&£  the  thumb.  15.  The  second  and  last  phalanx  of  the  thumb. 


196  THE    METACARPUS. 

the  metacarpal  bones,  appears  like  the  side  of  an  arch,  which 
is  partly  induced  by  the  wedge-like  form  of  the  two  bones  in 
the  centre ;  viz.,  the  trapezoides,  and  the  magnum.  When 
the  hand  hangs  by  the  side,  and  the  palm  is  forward,  all  of  this 
surface  presents  downwards,  except  that  portion  of  it  which  is 
formed  by  the  trapezium.  This  bone  is  placed  obliquely 
between  the  two  rows,  and  its  gurface  for  supporting  the  thumb 
presents  obliquely  downwards  and  outwards. 

The  trapezoides  supports  the  fore-finger,  the  magnum  the 
middle  finger. 

The  scaphoides  and  the  trapezium  are  very  prominent  at 
the  external  side  of  the  anterior  concave  surface  of  the  car- 
pus ;  and  the  unciforme  process,  and  the  os  pisiforme  on  the 
internal. 

The  Metacarpus, 

Consists  of  four  bones,  which  sustain  the  finger.  Each  bone 
is  long  and  round,  with  its  ends  larger  than  its  body.  The 
upper  end,  which  some  call  the  base,  is  flat  and  oblong,  in- 
clining somewhat  to  the  wedge-like  form,  without  any  con- 
siderable head  or  cavity ;  but  it  is,  however,  somewhat 
hollowed  for  the  articulation  with  the  carpus.  It  is  made  flat 
and  smooth  on  the  sides  where  these  bones  are  contiguous  to 
each  other.  Their  bodies  are  flattened  on  the  back  part, 
particularly  below  the  middle,  by  tendons  of  the  extensors  of 
the  fingers.  The  anterior  surface  of  these  bodies  is  a  little 
convex,  especially  in  their  middle ;  along  which  a  sharp  ridge 
stands  out,  separating  the  musculi  interossei  placed  on  each 
side  of  these  bones,  which  are  there  made  flat  and  plain  by 
these  muscles. 

Their  lower  ends  are  raised  into  large  oblong  smooth  heads, 
whose  greatest  extent  is  forwards  from  the  axis  of  the  bone. 
At  the  forepart  of  each  side  of  the  root  of  these  heads,  one  or 
two  tubercles  stand  out,  for  fixing  the  ligaments  that  go  from 
one  metacarpal  bone  to  another,  to  preserve  them  from  being 
drawn  asunder.  Around  the  heads  a  rough  ring  may  be 


THE    METACARPUS,  197 

remarked,  for  the  capsular  ligaments  of  the  first  joints  of  the 
fingers  to  be  fixed  to ;  and  both  sides  of  these  heads  are  flat,  by 
pressing  on  each  other.  s 

The  substance  of  the  metacarpal  bones  is  the  same  with  that 
of  all  long  bones. 

The  metacarpal  bones  are  joined  above  to  the  bones  of  the 
carpus,  and  to  each  other  by  surfaces  almost  flat.  These  con- 
nexions do  not  admit  of  much  motion.  The  articulation  of  the 
round  heads,  at  their  lower  ends,  with  the  cavities  of  the  first 
bones  of  the  fingers,  will  soon  be  described. 

The  concavity  on  the  forepart  of  the  metacarpal  bones,  and 
the  position  of  their  basis  on  the  arched  carpus,  cause  them  to 
form  a  hollow  in  the  palm  of  the  hand,  which  is  often  useful 
to  us.  The  spaces  between  them  lodge  muscles,  and  their 
small  motion  makes  them  fit  supporters  for  the  fingers  to  play 
on. 

Though  the  ossa  metacarpi  so  far  agree,  yet  they  may  be  dis- 
tinguished from  each  other  by  the  following  marks  : 

The  metacarpal  bone  of  the  fore-finger  is  generally  the 
longest.  Its  base,  which  is  articulated  with  the  os  trapezoides, 
is  hollow  in  the  middle.  The  small  ridge  on  the  external  side 
of  this  oblong  cavity  is  smaller  than  the  one  opposite  to  it,  and 
is  made  flat  on  the  side  by  the  trapezium.  The  internal  ridge 
is  also  smooth,  and  flat  on  its  ulnar  side,  for  its  conjunction 
with  the  os  magnum  ;  immediately  below  which,  a  semicircular 
smooth  flat  surface  shows  the  articulation  of  this  to  the  second 
metacarpal  bone.  The  back  part  of  this  base  is  flattened  where 
the  long  head  of  the  extensor  carpi  radialis  is  inserted,  and  its 
forepart  is  prominent  where  the  tendon  of  the  flexor  carpi  radialis 
is  fixed.  The  tubercle  at  the  internal  root  of  its  head  is  larger 
than  the  external.  Its  base  is  so  firmly  fixed  to  the  bone  it  is 
connected  with,  that  it  has  no  motion. 

The  metacarpal  bone  of  the  middle  finger  is  generally  the 
second  in  length ;  but  often  it  is  as  long  as  the  former :  some- 
times it  is  longer ;  and  it  frequently  appears  only  to  equal  the 
first  by  the  os  magnum  being  farther  projected  downwards 
than  any  other  bone  of  the  wrist.  Its  base  is  a  broad  super- 
17* 


198  THE    METACARPUS. 

ficial  cavity,  slanting  inwards  ;  the  external  posterior  angle  of 
which  is  so  prominent,  as  to  have  the  appearance  of  a  process. 
The  external  side  of  this  base  is  made  plane  in  the  same  way 
as  the  external  side  of  the  former  bone,  while  its  internal  side 
has  two  hollow  circular  surfaces,  for  joining  the  third  metacarpal 
bone  ;  and  between  these  surfaces  there  is  a  rough  fossa,  for  the 
adhesion  of  a  ligament,  and  lodging  mucilaginous  glands.  The 
extensor  carpi  radialis  brevior  is  inserted  into  the  back  part  of 
this  base.  The  two  sides  of  this  bone  are  almost  equally  flat- 
tened ;  but  the  ridge  on  the  forepart  of  the  body  inclines  inwards. 
The  tubercles  at  the  forepart  of  the  root  of  the  head  are  equal. 
The  motion  of  this  bone  is  very  little  more  than  that  of  the 
former ;  and  therefore  these  two  firmly  resist  bodies  pressed 
against  them  by  the  thumb  or  fingers,  or  both. 

The  metacarpal  bone  of  the  ring  finger  is  shorter  than  the 
second  metacarpal  bone.  Its  base  is  semicircular  and  convex, 
for  its  conjunction  with  the  os  unciforme.  On  its  external  side 
are  two  smooth  convexities,  and  a  middle  fossa,  adapted  to  the 
second  metacarpal  bone.  The  internal  side  has  a  triangular 
smooth  concave  surface  to  join  it  with  the  fourth  one.  The 
anterior  ridge  of  its  body  is  situated  more  to  the  inside  than  to 
the  outside.  The  tubercles  near  the  head  are  equal.  The  mo- 
tion of  this  third  metacarpal  bone  is  greater  than  the  motion  of 
the  second. 

The  metacarpal  bone  of  the  little  finger  is  the  smallest  and 
sharpest.  Its  base  is  irregularly  convex,  and  rises  slanting 
inwards.  Its  external  side  is  exactly  adapted  to  the  third  meta- 
carpal bone.  The  internal  has  no  smooth  surface,  because  it  is 
not  contiguous  to  any  other  bone  ;  but  it  is  prorninent  where 
the  extensor  carpi  ulnaris  is  inserted.  As  this  metacarpal  bone 
is  furnished  with  a  proper  moving  muscle,  has  the  plainest  articu- 
lation, is  most  loosely  connected  and  least  confined,  it  not  only 
enjoys  a  much  larger  motion  than  any  of  the  rest,  but  draws 
the  third  bone  with  it,  when  the  palm  of  the  hand  is  to  be  made 
hollow  by  its  advancement  forwards,  and  by  the  prominence  of 
the  thumb  opposite  to  it. 


THUMB    AND    FINGERS.  199 


Thumb  and  Fingers. 

The  thumb  and  fore-fingers  are  each  composed  o£  three 
bones. 

The  THUMB  is  situated  obliquely  in  respect  to  the  fingers  ; 
neither  opposite  directly  to  them,  nor  in  the  same  plane 
with  them.  All  its  bones  are  much  thicker  and  stronger  in 
proportion  to  their  length,  than  the  bones  of  the  fingers  are  ; 
which  is  extremely  necessary,  as  the  thumb  counteracts  all  the 
fingers. 

The  first  bone  of  the  thumb  has  its  base  adapted  to  the  pecu- 
liar articulating  surface  of  the  trapezium  :  for,  in  viewing  it  from 
one  side  to  the  other,  it  appears  convex  in  the  middle  ;  but, 
when  viewed  from  behind  forwards,  it  is  concave  there.  The 
edge  at  the  forepart  of  this  base  is  extended  farther  than  any 
other  part  ;  and  round  the  back  part  of  the  base  a  rough  fossa 
may  be  seen,  for  the  connexion  of  the  ligaments  of  this  joint. 
The  body  and  head  of  this  bone  are  of  the  same  shape  as  the 
ossa  metacarpi ;  only  that  the  body  is  shorter,  the  head  flatter, 
and  tubercles  at  the  forepart  of  its  root  larger. 

The  articulation  of  the  upper  end  of  this  bone  is  remarkable ; 
for,  though  it  has  protuberances  and  depressions  adapted  to  the 
double  pulley  of  the  trapezium,  yet  it  enjoys  a  circular  motion, 
as  the  joints  do  where  a  round  head  of  the  one  plays  in  the 
orbicular  socket  of  another ;  it  is,  however,  more  confined,  and 
less  expeditious,  but  stronger  and  more  secure  than  such  joints 
generally  are. 

The  second  bone  of  the  thumb  has  a  large  base  formed  into 
an  oblong  cavity,  whose  greatest  length  is  from  one  side  to  the 
other.  Round  it  several  tubercles  may  be  remarked,  for  the 
insertion  of  ligaments.  Its  body  is  convex,  or  half  round  behind  ; 
but  flat  before,  for  lodging  the  tendon  of  the  long  flexor,  of  the 
thumb,  which  is  tied  down  by  ligamentous  sheaths,  that  are 
fixed  on  each  side  to  the  angle  at  the  edge  of  this  flat  surface. 
The  lower  end  of  this  second  bone  has  two  lateral  round  protu- 
berances, and  a  middle  cavity,  whose  greatest  extent  of  smooth 
surface  is  forwards  and  backwards. 


200  FINGERS. 

The  articulation  of  the  upper  end  of  this  second  bone  would 
seem  calculated  for  motion  in  all  directions  ;  yet,  on  account  of 
the  strength  of  its  lateral  ligaments,  the  oblong  figure  of  the  joint 
itself,  and  mobility  of  the  first  joint,  it  only  allows  flexion  and 
extension  ;  and  these  are  generally  much  confined. 

The  third  bone  of  the  thumb  is  the  smallest,  with  a  larse  base, 

•/  O  * 

whose  greatest  extent  is  from  oj?e  side  to  the  other.  This  base 
is  formed  into  two  cavities  and  a  middle  protuberance,  to  be 
adapted  to  the  pulley  of  the  former  bone.  This  bone  becomes 
gradually  smaller,  till  near  the  lower  end,  where  it  is  a  little 
enlarged,  and  has  an  oval  scabrous  edge.  Its  body  is  rounded 
behind,  but  is  flatter  than  in  the  former  bone,  for  sustaining  the 
nail.  It  is  flat  and  rough  before,  by  the  insertion  of  the  flexor 
longus  pollicis. 

The  motion  of  this  third  bone  is  confined  to  flexion  and 
extension. 

The  regular  arrangement  of  the  bones  of  the  FINGERS  in  three 
rows,  has  obtained  for  them  the  name  of  the  three  phalanges. 
All  of  them  have  half  round  convex  surfaces,  covered  with  an 
aponeurosis,  formed  by  the  tendons  of  the  extensors,  lumbri- 
cales,  and  interossei,  and  placed  directly  backwards,  for  their 
greater  strength  ;  and  their  flat  concave  part  is  forwards,  for 
taking  hold  more  surely,  and  for  lodging  the  tendons  of  the 
flexor  muscles.  The  ligaments  for  keeping  down  these  tendons 
are  fixed  to  the  angles  that  are  between  the  convex  and  concave 
sides. 

The  bones  of  the  first  phalanx  of  the  fingers  answer  to  the 
description  of  the  second  bone  of  the  thumb  ;  only  that  the 
cavity  in  their  base  is  not  so  oblong  ;  nor  is  their  motion  on  the 
metacarpal  bones  so  much  confined  ;  for  they  can  move  laterally 
or  circularly,  the  fore-finger  in  particular,  but  have  no  rotation, 
or  a  very  small  degree  of  it,  round  their  axis. 

The  second  bone  of  the  fingers  has  its  base  formed  into  two 
lateral  cavities,  and  a  middle  protuberance :  while  the  lower 
end  has  two  lateral  protuberances,  and  a  middle  cavity  :  there- 
fore, it  is  joined  at  both  ends  in  the  same  manner ;  which  none 
of  the  bones  of  the  thumb  are. 


THE  THIGH.  201 

The  third  bone  differs  in  nothing  from  the  description  of  the 
third  bone  of  the  thumb,  except  in  the  general  distinguishing 
marks ;  and,  therefore,  the  second  and  third  phalanx  -6f  the 
fingers  enjoy  only  flexion  and  extension. 

All  the  difference  of  the  phalanges  of  the  several  fingers 
consists  in  their  magnitude.  The  bones  of  the  middle  finger 
being  the  longest  ancf  largest ;  those  of  the  fore-finger  come  next 
to  these  in  thickness,  but  not  in  length,  for  those  of  the  ring 
finger  are  a  little  longer.  The  little  finger  has  the  smallest 
bones.  This  disposition  is  the  best  contrivance  for  holding  the 
largest  bodies ;  because  the  longest  fingers  are  applied  to  the 
middle  largest  periphery  of  such  substances  as  are  of  a  spherical 
figure. 

The  Inferior  Extremities. 

The  inferior  extremities  consist  of  the  THIGH,  LEG,  and 
FOOT. 

The  Thigh 

Consists  of  one  bone  only ;  the  os  femoriSj  which  is  very 
strong,  and  larger  than  any  other  in  the  skeleton.  It  is  nearly 
cylindrical  in  the  middle,  and  slightly  curved.  The  upper 
extremity  is  a  spherical  head,  connected  to  the  body  of  the  bone 
by  a  neck.  The  lower  extremity  is  much  larger  than  the  body, 
and  is  formed  into  two  condyles. 

The  upper  end  of  this  bone  is  not  continued  in  a  straight  line 
with  the  body  of  it,  but  the  axis  of  it  inclines  obliquely  inwards 
and  upwards,  whereby  the  distance  between  these  two  bones,  at 
their  upper  part,  is  considerably  increased.  The  head  is  the 
greater  portion  of  a  sphere.  Towards  its  lower  internal  part, 
a  round,  rough  spongy  pit  is  observable,  where  the  strong 
ligament,  commonly,  but  inaccurately,  called  the  round  one,  is 
fixed,  to  be  extended  from  thence  to  the  lower  internal  part  of 
the  receiving  cavity,  where  it  is  considerably  broader  than  near 
to  the  head  of  the  thigh  bone.  The  neck  of  the  os  femoris  has 
a  great  many  large  holes,  into  which  the  fibres  of  the  strong 


202 


THE  THIGH. 


ligament,  continued  from  the  capsular,  enter,  and  are  thereby 
firmly  united  to  it ;  and  round  the  root  of  the  neck,  where  it 
rises  from  the  bone,  a  rough  ridge  is  found,  where  the  capsular 
Fig.  45.*  ligament  of  the  articulation  itself  is  con- 
nected. Below  this  root,  a  large  unequal 
protuberance,  called  trochanter  major, 
stands  out  ;.  the  external  convex  part  of 
which  is  distinguished  into  three  different 
surfaces;  whereof  the  one  on  the  upper  and 
front  part  is  scabrous  and  rough,  for  the 
insertion  of  the  glutaeus  minimus ;  the  supe- 
rior one  is  smooth,  and  has  the  glutaeus 
medius  inserted  into  it ;  and  the  one  behind 
is  made  flat  and  smooth,  by  the  tendon  of 
the  glutaeus  maximus  passing  over  it.  The 
upper  edge  of  this  process  is  sharp  and 
pointed  at  its  back  part,  where  the  glutaeus 
medius  is  fixed ;  but  forwards  it  is  more 
obtuse,  and  under  it  is  a  depression,  into 
which  some  of  the  muscles,  which  rotate 
the  thigh  outwards,  are  fixed.  From  the 
posterior  prominent  part  of  this  great  tro- 
chanter, a  rough  ridge  runs  backwards  and 
downwards,  into  which  the  quadratus  is 
inserted.  In  the  deep  hollow,  at  the  inter- 
nal upper  side  of  this  ridge,  the  obturator 
externus  is  implanted.  More  internally,  a  conical  process, 
called  trochanter  minor,  rises,  for  the  insertion  of  the  musculus 
psoas  and  iliacus  internus ;  and  the  pectineus  is  implanted  into 
a  rough  hollow,  below  its  internal  root.  The  muscles  inserted 
into  these  processes  being  the  principal  instruments  of  the 


*  The  right  femor,  seen  upon  the  anterior  aspect.  I.  The  shaft.  2.  The  head. 
3.  The  neck.  4.  The  great  trochanter.  5.  The  anterior  intertrochanteric  line. 
6.  The  lesser  trochanter.  7.  The  external  condyle.  8.  The  internal  condyle. 
9.  The  tuberosity  for  the  attachment  of  the  external  lateral  ligaments.  10.  The 
groove  for  the  tendon  of  origin  of  the  popliteus  muscle.  11.  The  tuberosity  for 
the  attachment  of  the  internal  lateral  ligament. 


OS    FEMORIS.  203 

y rotary  motion  of  the  thigh,  have  occasioned  the  name  of  trochan- 
ters  to  be  given  to  these  processes. 

The  body  of  the  os  femoris  is  convex  on  the  forepart  and 
concave  behind,  which  enables  us  to  sit  without  leaning  too 
much  on  the  posterior  muscles. 

On  the  posterior  concave  surface  is  a  broad  rough  ridge  called 
lima  aspera,  which  commences  near  the  great  trochanter,  and 
continues  downwards,  more  than  two-thirds  of  the  length  of 
the  bone,  when  it  divides  into  two  ridges,  which  descend 
towards  each  condyle.  The  internal  of  these  ridges  is  the  most 
smooth,  and  the  space  between  them  is  nearly  flat.  Near  the 
end  of  each  of  these  ridges,  a  small,  smooth-protuberance  may 
often  be  remarked,  where  the  two  heads  of  the  external  gastroc- 
nemius  muscles  take  their  rise ;  and  from  the  forepart  of  the 
internal  tubercle,  a  strong  ligament  is  extended  to  the  inside  of 
the  tibia. 

The  lower  end  of  the  os  femoris  is  larger  than  any  other  part 
of  it,  and  is  formed  into  two  great  protuberances,  one  on  each 
side,  which  are  called  its  condyles  :  between  them  a  considerable 
cavity  is  found,  especially  at  the  back  part,  in  which  the  crural 
vessels  and  nerves  lie.  The  internal  condyle  is  longer  than  the 
external,  which  must  happen  from  the  oblique  position  of  this 
bone,  to  give  less  obliquity  to  the  leg.  These  processes  are  of 
an  oblong  form,  and  are  placed  obliquely  with  respect  to  each 
other ;  being  in  contact  before  and  separated  to  a  considerable 
distance  behind. 

They  form  in  front  a  smooth  pulley-like  surface,  the  external 
side  of  which  is  highest,  on  which  the  patella  moves. 

Below,  they  are  flat ;  and  posteriorly,  they  are  regularly 
convex. 

Between  these  convex  portions  is  a  rough  cavity,  from  which 
the  crucial  ligament  arises,  to  be  attached  to  the  tibia.  Round 
the  lower  end  of  the  thigh  bone,  large  holes  are  found,  into 
which  the  ligaments  for  the  security  of  the  joint  are  fixed,  and 
blood-vessels  pass  to  the  internal  substance  of  the  bone. 

The  thigh  bone  being  articulated  above  with  the  acetabulum 
of  the  os  innominatum,  which  affords  its  round  head  a  secure 
and  extensive  play,  can  be  moved  to  every  side :  but  it  is 


204  THE    LEG. 

restrained  in  its  motion  outwards  by  the  high  brims  of  the 
cavity,  and  by  the  round  ligament ;  for  otherwise  the  head  of 
the  bone  would  have  been  frequently  thrust  out  at  the  breach  of 
the  brims  on  the  inside,  which  allows  the  thigh  to  move  consider- 
ably inwards.  The  body  of  this  bone  enjoys  little  or  no 
rotary  motion,  though  the  head  most  commonly  moves  round  its 
own  axis ;  because  the  oblique  direction  of  the  neck  and  head 
from  the  bone,  is  such,  that  the  rotary  motion  of  the  head  can 
only  bring  the  body  of  .the  bone  forwards  and  backwards.  Nor 
is  the  head,  as  in  the  arm,  ever  capable  of  being  brought  to  a 
straight  direction  with  its  body  ;  so  far,  however,  as  the  head  can 
move  within  the  cavity  backwards  and  forwards,  the  rest  of  the 
bone  may  have  a  partial  rotation. 

From  the  oblique  position  of  these  bones  it  results,  that  there 
is  a  considerable  distance  between  them  above,  while  the  knees 
are  almost  contiguous.  Sufficient  space  is  thereby  left  for  the 
external  parts  of  generation,  for  the  two  great  outlets  of  urine 
and  faeces,  and  for  the  large  thick  muscles  that  move  the  thigh 
inwards.  At  the  same  lime  this  situation  of  the  thigh  bone 
renders  our  progression  quicker,  surer,  straighter,  and  in  less 
room :  for,  had  the  knees  been  at  a  greater  distance  from  each 
other,  we  must  have  been  obliged  to  describe  some  part  of  a 
circle  with  the  trunk  of  our  body  in  making  a  long  step ;  and 
when  one  leg  was  raised  from  the  ground,  our  centre  of  gravity 
would  have  been  too  far  from  the  base  of  the  other,  and  we 
should  consequently  have  been  in  danger  of  falling  ;  so  that  our 
steps  would  neither  have  been  straight  nor  firm,  nor  would  it 
have  been  possible  to  walk  in  a  narrow  path,  had  our  thigh 
bones  been  otherwise  placed.  In  consequence,  however,  of  the 
weight  of  the  body  bearing  so  obliquely  on  the  joint  of  the  knee 
by  this  situation  of  the  thigh  bones,  weak  rickety  children 
become  knock-kneed. 


The  Leg 

Is  composed  of  the  two  bones,  the  TIBIA  and  FIBULA. 
The   patella  being  evidently  appropriated  to  the  knee-joint, 
may  be  regarded  as  common  both  to  the  thigh  and  leg. 


THE    TIBIA. 


205 


Fig.  46, 


The  Tibia 


Is  the  long  thick  triangular  bone,  situated 
at  the  internal  part  of  the  leg,  and  continued 
in  almost  a  straight  line  from  the  thigh 
bone.  The  name  is  derived  from  i'ts  resem- 
blance to  the  ancient  musical  instrument. 

The  upper  end  of  the  tibia  is  large,  bul- 
bous, and  spongy.  It  has  a  horizontal  sur- 
face, divided  into  two  cavities,  by  a  rough, 
irregular  protuberance,  which  is  hollow  at 
its  most  prominent  part,  as  well  as  before  and 
behind.  The  anterior  of  the  two  ligaments 
that  compose  the  great  crucial  is  inserted 
into  the  middle  cavity  ;  and  the  depression 
behind  receives  the  posterior  ligament.  The 
two  broad  cavities  at  the  sides  of  this  pro- 
tuberance are  not  equal ;  for  the  internal  is 
oblong  and  deep,  to  receive  the  internal 
condyle  of  the  thigh  bone  ;  while  the  exter- 
nal is  more  superficial  and  round,  for  the 
external  condyle.  In  each  of  these  two  cavities  of  a  recent 
subject,  a  semilunar  cartilage  is  placed,  which  is  thick  at  its 
convex  edge,  and  becomes  gradually  thinner  towards  the  con- 
cave or  interior  edge.  The  thick  convex  edge  of  each  cartilage 
is  connected  to  the  capsular  and  other  ligaments  of  the  articu- 
lation ;  but  so  near  to  their  rise  from  the  tibia,  that  the  cartilages 
are  not  allowed  to  change  their  places;  while  their  narrow  ends 
are  fixed  at  the  insertion  of  the  strong  cross  ligament  into  the 
tibia,  and  seem  to  have  their  substance  united  with  it ;  there- 
fore a  circular  hole  is  left  between  each  cartilage  and  the 
ligament,  in  which  the  most  prominent  convex  part  of  each 


*  The  tibia  and  fibula  of  the  right  leg,  articulated  and  seen  from  the  front. 
1.  The  shaft  of  the  tibia.  2.  The  inner  tuberosity.  3.  The  outer  tnberosity. 
4.  The  spinous  process.  5.  The  tubercle.  6.  The  internal  or  subcutaneous 
surface  of  the  shaft.  7.  The  lower  extremity  of  the  tibia.  8.  The  internal 
malleolus.  9.  The  shaft  of  the  fibula.  10.  Its  upper  extremity.  11.  Its  lower 
extremity,  the  external  malleolus. 
18 


206  TIBIA. 

condyle  of  the  thigh  bone  moves.  The  circumference  of  these 
cavities  is  rough  and  unequal,  for  the  firm  connexion  of  the 
ligaments  of  the  joint.  Immediately  below  the  edge,  at  its 
back  part,  two  rough  flattened  protuberances  stand  out ;  into 
the  internal,  the  tendon  of  the  semimembranosus  muscle  is 
inserted  ;  and  a  part  of  the  cross  ligament  is  fixed  to  the  exter- 
nal. On  the  outside  of  this  last  tubercle,  a  smooth  slightly 
hollowed  surface  is  formed  by  the  action  of  the  popliteus 
muscle. 

Before  the  forepart  of  the  upper  end  of  the  tibia,  a  large 
rough  protuberance  rises,  to  which  the  strong  tendinous  liga- 
ment of  the  patella  is  fixed.  On  the  internal  side  of  this,  there 
is  a  broad  scabrous  slightly  hollowed  surface,  to  which  the 
internal  long  ligament  of  the  joint,  the  aponeurosis  of  the  vastus 
internus,  and  the  tendons  of  the  semitendinous,  gracilis,  and 
sartorius,  are  fixed.  Below  the  external  edge  of  the  upper 
end  of  the  tibia,  there  is  a  flat  circular  surface,  covered  in  a 
recent  subject  with  cartilage,  for  the  articulation  of  the  fibula. 
The  body  of  the  tibia  is  triangular.  The  anterior  angle  is  very 
sharp,  and  is  commonly  called  the  spine  or  shin.  This  ridge  is 
not  straight ;  but  turns  first  inwards,  then  outwards,  and  lastly 
inwards  again.  The  plane  internal  side  is  smooth  and  equal, 
being  little  subjected  to  the  actions  of  muscle ;  but  the  external 
side  is  hollowed  above  by  the  tibialis  anticus,  and  below  by 
the  extensor  digitorum  longus  and  extensor  pollicis  longus. 
The  two  angles  behind  these  sides  are  rounded  by  the  action 
of  the  muscles ;  the  posterior  side  comprehended  between  them 
is  not  so  broad  as  those  already  mentioned,  but  is  more  oblique 
and  flattened  by  the  action  of  the  tibialis  posticus  and  flexor 
digitorum  longus.  A  little  above  the  middle  of  the  bone,  the 
internal  angle  terminates,  and  the  bone  is  made  round  by 
the  pressure  of  the  musculus  soleus.  Near  to  this,  the 
passage  of  the  medullary  vessels  is  seen  slanting  obliquely 
downwards. 

The  lower  end  of  the  tibia  is  hollowed,  with  a  small  protu- 
berance in  the  middle.  The  internal  side  of  this  cavity,  which 
is  smooth,  and  in  a  recent  subject  is  covered  with  cartilage,  is 


FIBULA.  207 

extended  into  a  considerable  process,  commonly  named  malleolus 
internus  ;  the  point  of  which  is  divided  by  a  notch,  and  from 
it  ligaments  are  sent  out  to  the  foot.  The  externafVide  of 
this  end  of  the  tibia  has  a  rough  irregular  cavity  formed  in  it, 
for  receiving  the  lower  end  of  the  fibula.  The  posterior  side 
has  two  lateral  grooves,  and  a  small  middle  protuberance.  In 
the  internal  depression,  the  tendons  of  the  musculus  tibialis 
posticis  and  flexor  digitorum  longus  are  lodged ;  and  in  the 
external,  the  tendon  of  the  flexor  longus  pollicis  plays.  From 
the  middle  protuberance,  ligamentous  sheaths  go  out,  for  tying 
down  these  tendons. 

The  Fibula 

Is  the  small  bone,  placed  on  the  outside  of  the  leg,  opposite  to 
the  external  angle  of  the  tibia ;  the  shape  of  it  is  irregular. 

The  head  of  the  fibula  has  a  circular  surface  formed  on  its 
inside,  which,  in  a  recent  subject  is  covered  with  a  cartilage ; 
and  it  is  so  closely  connected  to  the  tibia  by  ligaments,  as  to 
allow  only  a  very  small  motion  backwards  and  forwards.  This 
head  is  protuberant  and  rough  on  its  outside,  where  a  strong 
round  ligament  and  the  musculus  biceps  are  inserted,  and, 
below  the  back  part  of  its  internal  side,  a  tubercle  may  be  re- 
marked, that  gives  rise  to  the  strong  tendinous  part  of  the  soleus 
muscle. 

The  body  of  this  bone  is  a  little  crooked  inwards  and  back- 
wards :  which  figure  is  owing  to  the  actions  of  the  muscles. 
The  sharpest  angle  of  the  fibula  is  forwards ;  on  each  side  of 
which  the  bone  is  considerably,  but  unequally,  depressed  by  the 
bellies  of  the  several  muscles  that  rise  from  or  act  upon  it.  The 
external  surface  of  the  fibula  is  depressed  obliquely  from  above 
downwards  and  backwards,  by  the  two  peronaei.  Its  internal 
surface  is  unequally  divided  into  two  narrow  longitudinal 
planes,  by  an  oblique  ridge  extended  from  the  upper  part  of 
the  anterior  angle.  To  this  ridge  the  ligament  stretched  between 
the  two  bones  of  the  leg  is  connected.  The  anterior  of  the 
two  planes  is  very  narrow  above,  where  the  extensor  longus 
digitorum  and  extensor  longus  pollicis  arise  from  it :  but  is 


208  FIBULA. 

broader  below,  where  it  has  the  print  of  the  peroneus  tertius. 
The  posterior  plane  is  broad  and  hollow,  giving  origin  to  the 
larger  share  of  the  tibialis  posticus.  The  internal  angle  of  this 
bone  has  a  tendinous  membrane  fixed  to  it,  from  which  some 
fibres  of  the  flexor  digitorum  longus  take  their  rise.  The 
posterior  surface  of  the  fibula  is  the  plainest  and  smoothest ; 
but  is  made  flat  above  by  the  splaeus,  and  is  hollowed  below  by 
the  flexor  pollicis  longus.  In  the  middle  of  this  surface, 
the  canal  for  the  medullary  vessels  may  be  seen  slanting 
downwards. 

The  lower  end  of  the  fibula  is  extended  into  a  spongy  oblong 
head :  on  the  inside  of  which  is  a  convex,  irregular,  and 
frequently  a  scabrous  surface,  that  is  received  by  the  external 
hollow  of  the  tibia,  and  so  firmly  joined  to  it  by  a  very  thin 
intermediate  cartilage  and  strong  ligaments,  that  it  scarce  can 
move.  Below  this  the  fibula  is  stretched  out  into  a  smooth 
coronoid  process,  covered  with  cartilage  on  its  internal  side, 
and  is  there  contiguous  to  the  outside  of  the  first  bone  of  the 
foot,  the  astragalus,  to  secure  the  articulation.  This  process, 
named  malleolus  externus,  being  situated  farther  back  than  is 
the  internal  malleolus,  and  in  an  oblique  direction,  obliges  us, 
naturally,  to  turn  the  forepart  of  the  foot  outwards.  At 
the  lower  internal  part  of  this  process,  a  spongy  cavity  for 
mucilaginous  glands  may  be  remarked  ;  from  its  point,  ligaments 
are  extended  to  the  bones  of  the  foot,  viz.  the  astragalus,  os 
calcis,  and  os  naviculare ;  and  from  its  inside,  short  strong  ones 
go  out  to  the  astragalus.  On  the  back  part  of  it  a  sinuosity  is 
made  by  the  tendons  of  the  peronei  muscles.  When  the 
ligament,  extended  over  these  tendons  from  the  one  side  of  the 
depression  to  the  other,  is  broken,  stretched  too  much,  or  made 
weak  by  the  sprain,  the  tendons  frequently  start  forwards  to  the 
outside  of  the  fibula. 

The  conjunction  of  the  upper  end  of  the  fibula  with  the 
tibia  is  by  plain  surfaces  tipped  with  cartilage  ;  and  at  its  lower 
end  the  cartilage  seems  to  glue  the  two  bones  together;  not, 
however,  so  firmly  in  young  people,  but  that  the  motion  at  the 
other  end  is  very  observable.  In  old  subjects,  the  two  bones 


THE  PATELLA  OR  ROTDLA.  209 

of  the   leg  are  sometimes  united  by  anchylosis  at  their  lower 
ends. 

The  principal  use  of  this  bone  is  to  afford  origin  arvd  inser- 
tion to  muscles  ;  and  to  give  a  particular  direction  to  their 
tendons.  It  likewise  assists  to  make  the  articulation  of  the 
foot  more  secure  and  firm,  and  to  complete  the  hinge-like  joint 
at  the  ankle.  The  ends  of  the  tibia  and  fibula  being  larger 
than  their  middle,  a  space  is  here  left,  which  is  filled  up  with 
a  ligament  similar  to  that  which  is  extended  between  the 
bones  of  the  forearm  ;  and  which  is  also  discontinued  at  its 
upper  part,  where  the  tibialis  anticus  immediately  adheres  to 
the  solaeus  and  tibialis  posticus  j  but  every  where  else  k  gives 
origin  to  muscular  fibres. 

The  Patella  or  Rotula 

Is  a  small  flat  bone  situated  at  the  forepart  of  the  joint  of 
the  knee.  Its  shape  resembles  the  common  figure  of  the  heart 
with  its  point  downwards.  The  anterior  convex  surface  of 
the  rotula  is  pierced  by  a  great  number  of  holes,  into  which 
are  inserted  the  fibres  of  the  strong  ligament  that  is  spread  over 
it.  Its  posterior  surface  is  smooth,  covered  with  a  cartilage, 
and  divided  by  a  middle  convex  ridge  into  two  cavities,  of 
which  the  external  is  the  largest ;  and  both  are  exactly  adapted 
to  the  pulley  of  the  os  femoris,  on  which  they  are  placed  in  the 
most  ordinary  unstraining  postures  of  the  legs :  but,  when  the 
leg  is  much  bent,  the  patella  descends  far  down  on  the  condyles  ; 
and  when  the  leg  is  fully  extended,  the  patella  rises  higher  in 
its  upper  part  than  the  pulley  of  the  thigh  bone.  The  plane 
smooth  surface  is  surrounded  by  a  rough  prominent  edge,  to 
which  the  capsular  ligament  adheres.  Below,  the  point  of  the 
bone  is  scabrous,  where  the  strong  tendinous  ligament  from  the 
tubercle  of  the  tibia  is  fixed.  The  upper  horizontal  part  of  this 
bone  is  flattened  and  unequal  where  the  tendons  of  the  exten- 
sors of  the  leg  are  inserted. 

The  substance  of  the  patella  is  cellular,  with  very  thin  firm 
external  plates  ;  but  then   these  cells  are  so  small  and  such  a 
quantity   of  bone  is    employed    in  their  formation,  that  scarce 
18* 


210  PATELLA. 

any  bone  of  its  bulk  is  so  strong.  But,  notwithstanding  this 
strength,  it  is  sometimes  broken  by  the  violent  straining  effort 
of  the  muscles. 

The  principal  motions  of  the  knee  joint  are  flexion  and 
extension.  In  the  former  of  these,  the  leg  may  be  brought  to 
a  very  acute  angle  with  the  thigh,  by  the  condyles  of  the  thigh 
bones  being  round,  and  made  smooth  far  backwards.  In 
performing  this,  the  patella  is  pulled  down  by  the  tibia.  When 
the  leg  is  to  be  extended,  the  patella  is  drawn  upwards,  conse- 
quently, the  tibia  forwards,  by  the  extensor  muscles;  which,  by 
means  of  the  protuberant  joint,  and  of  this  thick  bone  wkh  its 
ligament,  have  the  chord,  with  which  they  act,  fixed  to  the 
tibia  at  a  considerable  angle,  and  act,  on  that  account,  with 
advantage ;  but  they  are  restrained  from  pulling  the  leg  farther 
than  to  a  straight  line  with  the  thigh,  by  the  posterior  part  of 
the  cross  ligament,  that  the  body  might  be  supported  by  a  firm 
perpendicular  column  :  for,  at  this  time,  the  thigh  and  leg  are 
as  little  movable  in  a  rotary  way,  or  to  either  side,  as  if  they 
were  one  continued  bone.  But,  when  the  joint  is  a  little  bent, 
the  rotula  is  not  tightly  braced,  and  the  posterior  ligament  is 
relaxed  ;  therefore,  this  bone  may  be  moved  a  little  to  either 
side,  or  with  a  small  rotation  in  the  superficial  cavities  of  the 
tibia ;  which  is  done  by  the  motion  of  the  external  cavity 
backwards  and  forwards,  the  internal  serving  as  a  sort  of  axis. 
Seeing,  then,  one  part  of  the  cross  ligament  is  situated  perpen- 
dicularly, and  the  posterior  part  is  stretched  obliquely  from  the 
internal  condyle  of  the  thigh  outwards,  that  posterior  part  of  the 
cross  ligament  prevents  the  leg  from  being  turned  much  inwards ; 
but  it  could  not  hinder  it  from  turning  outwards  almost  round, 
were  not  that  motion  confined  by  the  lateral  ligaments  of  this 
joint,  which  can  yield  little. 

This  rotation  of  the  leg  outwards  is  of  great  advantage  to  us 
in  crossing  our  legs,  and  turning  our  feet  outwards,  on  several 
necessary  occasions  ;  though  it  is  necessary  that  this  motion 
should  not  be  very  large,  to  prevent  frequent  luxations  here. 
While  all  these  motions  are  performing,  the  part  of  the  tibia 
that  moves  immediately  on  the  condyles  is  that  which  is  within 


THE    FOOT. TARSUS. 


211 


the  cartilaginous  rings,  which,  by  the  thickness  on  their  out- 
sides,  make  the  cavities  of  the  tibia  more  horizontal,  by 
raising  their  external  side  where  the  surface  of  the  tibia/  slants 
downwards.  By  these  means  the  motions  of  this  joint  are 
more  equal  and  steady  than  otherwise  they  would  have  been. 
The  cartilages  being  capable  of  changing  a  little  their  situation, 
contribute  to  the  different  motions  and  postures  of  the  limb,  and, 
likewise,  make  the  motions  larger  and  quicker. 

The  Foot. 

The  foot  is  divided  into  the  tarsus,  metatarsus,  and  toes. 
The   sole  of  the  foot  is  necessarily  described  as  the  inferior 
part,  and  the  side  of  the  great  toe  as  the  internal. 


Fig.  47, 


Tarsus. 

The  tarsus  consists  of  seven  spongy 
bones ;  to  wit,  the  astragalus,  os  cakis, 
naviculare,  cuboides,  cuneiforme  externum, 
cuneiforme  medium  and  cuneiforme  inter- 
num. 

The  astragalus  is  the  uppermost  of 
these  bones.  The  os  calcis  is  below  the 
astragalus,  and  forms  the  heel.  The  os 
naviculare  is  in  the  middle  of  the  internal 
sides  of  the  tarsus.  The  os  cuboides  is  the 
most  external  of  the  row  of  four  bones,  at 
its  forepart.  The  os  cuneiforme  externum  is 
placed  at  the  inside  of  the  cuboid.  The 
cuneiforme  medium  is  between  the  external 
and  internal  cuneiforme  bones ;  and  the 
internal  cuneiforme  is  at  the  internal  side  of 
the  foot. 

The  upper  part  of  the  astragalus  is  formed 

*  The  dorsal  surface  of  the  left  foot.  i.  The  astragalus  j  its  superior  quadri- 
lateral articular  surface.  2.  The  anterior  extremity  of  the  astragalus,  which 
articulates  with  (4.)  the  scaphoid  bone.  3.  The  os  calcis.  4.  The  scaphoid  bone. 
5.  The  internal  cuneiform  bone.  6.  The  middle  cuneiform  bone.  7.  The  exter- 
nal cuneiform  bone.  8.  The  cuboid  bone.  9.  The  metatarsal  bones  of  the  first 
and  second  toes.  10.  The  first  phalanx  of  the  great  toe.  11.  The  second  pha- 
lanx of  th3  great  toe.  12.  The  first  phalanx  of  the  second  toe.  13.  Its  second 
phalanx.  14.  Its  third  phalanx. 


212  ASTRAGALUS. 

into  a  large  smooth  head,  which  is  slightly  hollowed  in  the 
middle ;  and  therefore  resembles  a  superficial  pulley,  by 
which  it  is  fitted  to  the  lower  end  of  the  tibia.  The  internal 
side  of  this  head  is  flat  and  smooth,  to  play  on  the  inter- 
nal malleolus.  The  external  side  has  also  such  a  surface, 
but  larger,  for  its  articulation  with  the  external  malleolus. 
Round  the  base  of  this  head  there  is  a  rough  fossa ;  and 
immediately  before  the  head,  as  also  below  its  internal  smooth 
surface,  we  find  a  considerable  rough  cavity. 

The  lower  surface  of  the  astragalus  is  divided  by  an  irregular 
deep  rough  fossa,  which,  at  its  internal  end,  is  narrow,  but 
gradually  widens  as  it  stretches  obliquely  outwards  and 
forwards.  The  smooth  surface,  covered  with  cartilage,  behind 
this  fossa,  is  large,  oblong,  extended  in  the  same  oblique  situa- 
tion with  the  fossa,  and  concave  for  its  conjunction  with  the 
os  calcis.  The  posterior  edge  of  this  cavity  is  formed  by  two 
sharp-pointed  rough  processes,  between  which  is  a  depression 
made  by  the  tendon  of  the  flexor  pollicis  longus.  The  lower 
surface  before  the  fossa  is  convex,  and  composed  of  three 
distinct  smooth  planes.  The  long  one  behind,  and  the  exterior 
or  shortest,  are  articulated  with  the  heel  bone ;  while  the 
internal,  which  is  the  most  convex  of  the  three,  rests  and  moves 
upon  a  cartilaginous  ligament,  that  is  continued  from  the  os 
calcis  to  the  os  naviculare,  without  which  ligament  the  astra- 
galus could  not  be  sustained,  but  would  be  pressed  out  of  its 
place  by  the  great  weight  it  supports;  and  the  other  bones  of 
the  tarsus  would  be  separated.  Nor  would  a  bone  be  fit  here, 
because  it  must  have  been  thicker  than  could  conveniently  be 
allowed  ;  otherwise  it  would  break,  and  would  not  prove  such 
an  easy  bending  base,  to  lessen  the  shock  which  is  given  to  the 
body,  in  leaping,  running,  &c. 

The  forepart  of  this  bone  is  formed  into  a  convex  oblong 
smooth  head,  which  is  received  by  the  os  naviculare,  and  is 
placed  obliquely ;  its  longest  axis  inclining  downwards  and 
inwards.  Round  the  root  of  this  head,  especially  on  the  upper 
surface,  a  rough  fossa  may  be  remarked. 

The  astragalus  is  articulated  above  to  the  tibia  and  fibula, 
which  together  form  one  cavity.  In  this  articulation,  flexion 


OS    CALCIS.  213 

and  extension  are  the  most  considerable  motions ;  the  other 
motions  being  restrained  by  the  malleoli,  and  by  the  strong 
ligaments  which  go  out  from  the  points  of  these  processes,  to 
the  astragalus  and  os  calcis.  When  the  root  is  bent,  as  it 
commonly  is  when  we  stand,  no  lateral  or  rotary  motion  is 
allowed  in  this  joint ;  for  then  the  head  of  the  astragalus  is  sunk 
deep  between  the  malleoli,  and  the  ligaments  are  tense :  but 
when  the  foot  is  extended,  the  astragalus  can  move  a  little  to 
either  side,  and  with  a  small  rotation.  By  this  contrivance,  the 
foot  is  firm,  when  the  weight  of  the  body  is  to  be  supported  on 
it ;  and,  when  a  foot  is  raised,  we  are  at  liberty  to  direct  it 
more  exactly  to  the  place  we  intend  next  to  step  upon. 

The  astragalus  is  joined  below  to  the  os  calcis  ;  and  before 
to  the  os  naviculare,  in  the  manner  to  be  explained  when  these 
bones  are  described. 

The  05  calcis  is  the  largest  bone  of  the  seven.  Behind,  it  is 
formed  into  a  large  knob,  commonly  called  the  heel,  the  poste- 
rior surface  of  which  is  rough  below  for  the  insertion  of  what 
is  called  the  tendo-achillis,  and  oblique  above  to  allow  the  heel 
to  be  depressed  without  pressing  against  the  tendon.  On  the 
upper  surface  of  the  os  calcis,  there  is  an  irregular  oblong 
smooth  convexity,  adapted  to  the  concavity  at  the  back  part  of 
the  astragalus  ;  and  beyond  this  a  narrow  fossa  is  seen,  which 
divides  it  from  two  small  concave  smooth  surfaces,  that  are 
joined  to  the  forepart  of  the  astragalus.  The  posterior  of  these 
smooth  surfaces,  which  is  the  largest,  is  the  upper  surface  of  a 
process  which  projects  inwards :  and  under  it  is  a  small 
sinuosity  for  the  tendon  of  the  flexor  digitorum  longus. 

The  external  side  of  this  bone  is  flat,  with  a  superficial  fossa 
running  horizontally,  in  which  the  tendon  of  the  musculus 
peroneus  longus  is  lodged.  The  internal  side  of  the  heel  bone 
is  hollowed,  for  lodging  the  origin  of  the  massa  carnea,  and  for 
the  safe  passage  of  tendons,  nerves,  and  arteries.  Under  the 
side  of  the  internal  smooth  concavity,  a  particular  groove  is 
made  by  the  tendon  of  the  flexor  pollicis  longus  ;  and  from  the 
thin  protuberance  of  this  internal  side  a  cartilaginous  ligament 
that  supports  the  astragalus,  goes  out  to  the  os  naviculare ;  on 


214  OS  NAV1CULARE. 

which  ligament,  and  on  the  edge  of  this  bone  to  which  it  is 
fixed,  the  groove  is  formed  for  the  tendon  of  the  flexor  digito- 
rum  profundus. 

The  lower  surface  of  this  bone  is  flat  at  the  back  part,  and 
immediately  before  this  plane,  there  are  two  tubercles,  from 
the  internal  of  which  the  musculus  abductor  pollicis,  flexor 
digitorum  sublimis,  as  also  p^rt  of  the  aponeurosis  plantaris, 
and  of  the  abductor  minimi  digiti,  have  their  origin  ;  and  the 
other  part  of  the  abductor  minimi  digiti  and  aponeurosis  plan- 
taris rises  from  the  external.  Before  these  protuberances,  this 
bone  is  concave,  for  lodging  the  flexor  muscles;  and,  at  its 
forepart,  we  may  observe  a  rough  depression,  from  which, 
and  a  tubercle  behind  it,  the  ligament  goes  out  that  prevents 
this  bone  from  being  separated  from  the  os  cuboides. 

The  forepart  of  the  os  calcis  is  formed  into  an  oblong  pulley- 
like  smooth  surface,  which  is  circular  at  its  upper  external  end, 
but  is  pointed  below.  The  smooth  surface  is  fitted  to  the  os 
cuboides. 

Though  the  surfaces  by  which  the  astragalus  and  os  calcis 
are  articulated,  seem  fit  enough  for  motion,  yet  the  very  strong 
ligaments,  by  which  these  bones  are  connected,  prevent  much 
motion,  and  give  firmness  to  this  principal  part  of  our  base, 
which  rests  on  the  ground. 

Os  naviculare^'is  somewhat  oval.  It  is  formed  into  an 
oblong  concavity  behind,  for  receiving  the  anterior  head  of  the 
astragalus.  The  upper  surface  is  convex.  Below,  the  surface 
is  very  unequal  and  rough ;  but  hollow  for  the  safety  of  the 
muscles.  Its  internal  extremity  is  very  prominent.  The 
abductor  pollicis  takes  in  part  its  origin  from  it,  the  tendon  of 
the  tibialis  posticus  is  inserted  into  it,  and  to  it  two  remarkable 
ligaments  are  fixed  ;  the  first  is  the  strong  one,  formerly  men- 
tioned, which  supports  the  astragalus  ;  the  second  is  stretched 
from  this  bone  obliquely  across  the  foot,  to  the  metatarsal  bones 
of  the  middle  toe,  and  of  the  toe  next  to  the  little  one.  On  the 
outside  of  the  os  naviculare  there  is  a  semicircular  smooth 
surface,  where  it  is  joined  to  the  os  cuboides.  The  forepart  of 
this  bone  is  covered  with  cartilage,  and  divided  into  three 
smooth  planes,  fitted  to  the  three  ossa  cuneiformia. 

i&    ivyti     ^j       LO^> 


OS  CUBOIDES. OS  CUNEIFORMS  EXTERNUM.       215 

• 

The  os  naviculare  and  astragalus  are  joined  as  a  ball  and 
socket ;  and  the  naviculare  moves  in  several  directions  in  turn- 
ing the  toes  inwards,  or  in  raising  or  depressing  either  ^ide  of 
the  foot,  though  the  motions  are  greatly  restrained  by  the  liga- 
ments which  connect  this  to  the  other  bones  of  the  tarsus. 

Os  Cuboides  is  an  irregular  cube.  Behind,  it  is  formed  into 
an  oblong  unequal  cavity,  adapted  to  the  forepart  of  the  os 
calcis.  On  its  internal  side,  there  is  a  small  semicircular  smooth 
cavity,  to  join  the  os  naviculare.  Immediately  before  which, 
an  oblong  smooth  plane  is  made  by  the  os  cuneiforme  exter- 
num  ;  below  this  the  bone  is  hollow  and  rough.  On  the  internal 
side  of  the  lower  surface,  a  round  protuberance  and  fossa  are 
found,  where  the  musculus  abductor  pollicis  has  its  origin.  On 
the  external  side  of  this  surface,  there  is  a  broad  ridge  running 
forwards  and  inwards,  covered  with  cartilage ;  immediately 
before  which  a  smooth  fossa  may  be  observed,  in  which  the 
tendon  of  the  peroneus  primus  runs  obliquely  across  the  foot. 
Before,  the  surface  of  the  os  cuboides  is  flat,  smooth,  and 
slightly  divided  into  two  planes,  for  sustaining  the  os  metatarsi 
of  the  little  toe,  and  of  the  toe  next  to  it. 

The  form  of  the  back  part  of  the  os  cuboides,  and  the  liga- 
ments connecting  the  joint  with  the  os  calcis,  both  concur  in 
allowing  little  motion  in  this  part. 

Os  cuneiforme  externum  is  shaped  like  a  wedge,  being 
broad  and  flat  above,  with  long  sides  running  obliquely  down- 
wards, and  terminating  in  an  edge.  The  upper  surface  of  this 
bone  is  an  oblong  square.  The  one  behind  is  nearly  a  triangle, 
but  not  complete  at  the  inferior  angle,  and  is  joined  to  the  os 
naviculare.  The  external  side  is  an  oblong  square  divided  as 
it  were  by  a  diagonal ;  the  upper  half  of  it  is  smooth,  for  its 
conjunction  with  the  os  cuboides  :  the  other  is  a  scabrous  hol- 
low, with  a  small  smooth  impression  made  by  the  os  metatarsi 
of  the  toe  next  to  the  little  one.  The  internal  side  of  this  bone 
is  flattened  before  by  the  metatarsal  bone  of  the  toe  next  to  the 
great  one,  and  the  back  part  is  also  flat  and  smooth  where  the  os 
cuneiforme  medium  is  contiguous  to  it.  The  forepart  of  this  bone 
is  triangular,  for  sustaining  the  os  metatarsi  of  the  middle  toe. 


216  OS    CUNEIFORMS. 

Os  cuneiforme,  or  minimum,  is  still  more  exactly  the  shape 
of  a  wedge  than  the  former.  Its  upper  part  is  square  ;  its  in- 
ternal side  has  a  flat  smooth  surface  for  its  connexion  with  the 
adjoining  bone;  the  external  side  is  smooth  and  a  little  hol- 
lowed, where  it  is  contiguous  to  the  last  described  bone.  Be- 
hind, this  bone  is  triangular,  where  it  is  articulated  with  the  os 
naviculare ;  and  it  is  also  triangular  at  its  forepart,  where  it  is 
contiguous  to  the  os  metatarsi  of  the  toe  next  to  the  great  one. 

The  broad  thick  part  of  the  os  cuneiforme  maximum,  or  in- 
ternum,  is  placed  below,  and  the  small  thinner  edge  is  above. 
The  surface  of  the  os  cuneiforme  behind,  where  it  is  joined  to 
the  os  naviculare,  is  hollow,  smooth,  and  of  a  circular  figure 
below,  but  pointed  above.  The  external  side  consists  of  two 
smooth  and  flat  surfaces.  With  the  posterior,  that  runs  ob- 
liquely forwards  and  outwards,  the  os  cuneiforme  minimum  is 
joined  ;  and  with  the  anterior,  whose  direction  is  longitudinal, 
the  os  metatarsi  of  the  toe  next  to  the  great  one  is  connected. 
The  forepart  of  this  bone  is  flat  and  smooth,  for  sustaining  the 
os  metatarsi  of  the  great  toe.  The  internal  side  is  scabrous, 
with  two  remarkable  tubercles  below,  from  which  the  muscu- 
lus  abductor  pollicis  rises,  and  the  tibialis  anticus  is  inserted 
into  its  upper  part. 

The  three  cuneiforme  bones  are  all  so  secured  by  ligaments, 
that  very  little  motion  is  allowed  in  any  of  them. 

These  seven  bones  of  the  tarsus,  when  joined,  are  convex 
above,  and  leave  a  concavity  below,  for  lodging  safely  the 
several  muscles,  tendons,  vessels,  and  nerves,  that  lie  in  the 
sole  of  the  foot.  In  the  recent  subject,  their  upper  and  lower 
surfaces  are  covered  with  strong  ligaments,  which  adhere  firmly 
to*  them ;  and  all  the  bones  are  so  tightly  connected  by  these 
and  the  other  ligaments,  which  are  fixed  to  the  rough  ridges 
and  fossae,  that  notwithstanding  the  many  surfaces  covered 
with  cartilage,  some  of  which  are  of  the  form  of  the  very 
movable  articulations,  no  more  motion  is  here  allowed,  than 
is  necessary  to  prevent  too  great  a  shock  of  the  fabric  of  the 
body  in  walking,  leaping,  &c.,  by  falling  on  too  solid  a  base. 
If  the  tarsus  was  one  continued  bone,  it  would  likewise  be 


METATARSUS. 


217 


much  more  liable  to  be  broken,  a-nd  the  foot  could  not  accom- 
modate itself  to  the  surfaces  we  tread  on  by  becoming  more 
or  less  hollow,  or  by  raising  or  depressing  either  of  its  sid^s. 

Metatarsus. 

The  Metatarsus  is  composed  of  five  bones,  which  agree,  in 
their  general  characters,  with  the  metacarpal  bones ;  but  may 
be  distinguished  from  them  by  the  following  marks :  1.  They 
are  longer,  thicker,  and  stronger.  2.  Their  anterior  round  ends 
are  not  so  broad,  and  are  less  in  proportion  to  their  basis. 

3.  Their  bodies   are   sharper  above   and  flatter  on  their  sides, 
with  their  inferior  ridge  inclined  more  to  the  outside.     4.  The 
tubercles  at  the  lower  part  of  the  round  head  are  larger. 

Fig.  48.*  The  first  or  internal  metatarsal  bone  is 

easily  distinguished  from  the  rest  by  its 
thickness.  The  one  next  to  it  is  the 
longest,  and  with  its  sharp  edge  almost 
perpendicular.  The  others  are  shorter 
and  more  oblique,  as  their  situation  is 
more  external.  Which  general  remarks, 
with  the  description  now  to  be  given  of 
each,  may  teach  us  to  distinguish  them 
from  each  other. 

Os  metatarsi  potticis  is  by  far  the. 
thickest  and  strongest,  as  having  much 
the  greatest  weight  to  sustain.  Its  base 
is  oblong,  irregularly  concave,  and  of  a 
semilunar  figure,  to  be  adapted  to  the  os 
cuneiforme  maximum.  •  The  inferior  edge 
of  this  base  is  a  little  prominent  and  rough, 

*  The  sole  of  the  left  foot.     1.  The  inner  tuberosity  of  the  os  calcis.    2.  The 
outer  tuberosity.     3.  The  groove  for  the  tendon  of  the  flexor  longus  digitorum. 

4.  The  rounded  head  of  the  astragalus.     5.  The  scaphoid  bone.     6.  Its  tuberosity. 
7.  The  internal  cuneiform  bone  ;  its  broad  extremity.     8.  The  middle  cuneiform 
bone.    9.  The  external  cuneiform  bone.     10,  11.  The  cuboid  bone.     11.  Refers 
to  the  groove  for  the  tendon  of  the  peroneus  longus.     12,  12.  The  metatarsal 
bones.     13,  13.  The  first  phalanges.     14,  14.  The  second  phalanges  of  the  four 
lesser  toes.     15,  15.  The  third,  or  uugual  phalanges  of  the  four  lesser  toes.     16» 
The  last  phalanx  of  the  great  toe. 

19 


218  METATARSUS. 

where  the  tendon  of  the  peroneus  primus  muscle  is  inserted. 
On  its  outside,  an  oblique  circular  depression  is  made  by  the 
second  metatarsal  bone.  Its  round  head  has  generally  on  its 
forepart  a  middle  ridge,  and  two  oblong  cavities,  for  the  ossa 
sesamoidea ;  and,  on  the  external  side,  a  depression  is  made  by 
the  following  bone. 

Os  metatarsi  of  the  second  tof  is  the  longest  of  the  five,  with 
a  triangular  base  supported  by  the  os  cuneiforme  medium,  and 
the  external  side  produced  into  a  process ;  the  end  of  which  is 
an  oblique  smooth  plane,  joined  to  the  os  cuneiforme  externum. 
Near  the  internal  edge  of  the  base,  this  bone  has  two  small 
depressions,  made  by  the  os  cuneiforme  maximum,  between 
which  is  a  rough  cavity.  Farther  forwards  we  may  observe 
a  smooth  protuberance,  which  is  joined  to  a  foregoing  bone. 
On  the  outside  of  the  base  are  two  oblong  smooth  surfaces  for 
its  articulation  with  the  following  bone ;  the  superior  smooth 
surface  being  extended  longitudinally,  and  the  inferior  perpendic- 
ularly, between  which  there  is  a  rough  fossa. 

Os  metatarsi  of  the  middle  toe  is  the  second  in  length.  Its 
base,  supported  by  the  os  cuneiforme  externum,  is  triangular, 
but  slanting  outwards,  where  it  ends  in  a  sharp-pointed  little 
process,  and  the  angle  below  it  is  not  completed. 

The  internal  side  of  this  base  is  best  adapted  to  the  preceding 
bone ;  and  the  external  side  has  also  two  smooth  surfaces 
covered  with  cartilage,  but  of  a  different  figure ;  for  the  upper 
one  is  concave,  and  being  round  behind,  turns  smaller  as  it 
advances  forwards;  and  the  lower  surface  is  a  little  smooth, 
convex,  and  very  near  the  edge  of  the  base. 

Os  metatarsi  of  the  fourth  toe  is  nearly  as  long  as  the  former, 
with  a  triangular  slanting  base  joined  to  the  os  cuboides,  and 
made  round  at  its  external  angle  ;  having  one  hollow  smooth 
surface  on  the  outside,  where  it  is  pressed  upon  by  the  following 
bone ;  and  two  on  the  internal  side,  corresponding  to  the  former 
bone,  behind  which  is  a  long  narrow  surface  impressed  by  the  os 
cuneiforme  externum. 

Os  metatarsi  of  the  little  toe  is  the  shortest,  situated  with 
its  two  flat  sides  above  and  below,  and  with  the  ridges  laterally 


STRUCTURE  OF   THE  FOOT.  219 

The  base  of  it,  part  of  which  rests  on  the  os  cuboides,  is  very 
large,  tuberous,  and  produced  into  a  long-pointed  process 
externally,  where  part  of  the  abductor  minimi  digiti  infixed; 
and  into  its  upper  part  the  peroneus  secundus  is  inserted.  Its 
inside  has  a  flat  conoidal  surface,  where  it  is  contiguous  to  the 
preceding  bone. 

When  we  stand,  the  fore  ends  of  these  metatarsal  bones, 
and  the  os  calcis,  are  our  only  supporters,  and,  therefore,  it  is 
necessary  that  they  should  be  strong,  and  should  have  a  confined 
motion. 

The  Toes. 

The  bones  of  the  toes  are  nearly  similar  to  those  of  the 
thumb  and  fingers ;  particularly  the  two  of  the  great  toe, 
which  are  precisely  formed  as  the  two  last  of  the  thumb ;  but 
their  position,  as  respects  the  other  toes,  is  not  oblique ;  and 
they  are  proportionally  much  stronger,  because  they  are  sub- 
jected to  a  greater  force  ;  for  they  sustain  the  impulse  by  which 
our  bodies  are  pushed  forwards  by  the  foot  behind  at  every 
step  we  make,  and  on  them  principally  the  weight  of  the  body 
is  supported,  when  we  are  raised  on  our  tip-toes. 

The  three  bones  in  each  of  the  other  four  toes,  compared 
with  those  of  the  fingers,  differ  from  them  in  these  particulars. 
They  are  less,  and  smaller  in  proportion  to  their  lengths.  Their 
basis  are  much  larger  than  their  anterior  ends.  The  first  pha- 
lanx is  proportionally  much  longer  than  the  bones  of  the  second 
and  third,  which  are  very  short. 

The  toe  next  to  the  great  one  has  the  largest  bones  in  all 
dimensions,  and  the  bones  of  the  other  toes  diminish  according 
to  the  order  of  their  position  ;  those  of  the  exterior  being  least. 

The  General  Structure  of  the  Foot. 

The  foot  may  be  considered  as  an  arch,  of  which  the  back 
part  of  the  heel,  and  the  anterior  extremities  of  the  metatarsal 
bones  and  the  toes,  are  the  abutments.  The  heel,  or  posterior 
abutment  is  not  so  broad  as  the  anterior,  and  is  placed  on  the 
outside  and  not  in  the  middle  of  the  extremity  of  the  arch.  The 


220  STRUCTURE  OF    THE  FOOT. 

process  on  the  inside  of  the  os  calcis,  which  supports  the 
astragalus,  increases  the  breadth  of  the  arch ;  and  the  os 
naviculare  completes  it.  The  arch,  thus  constructed,  does  not 
appear  very  firm,  and  this  apparent  want  of  strength  seems 
increased  by  the  position  of  the  anterior  portion  of  the  astra- 
galus, a  part  of  which  is  between  the  os  calcis  and  os  naviculare, 
and  not  supported  by  either.  These  bones,  however,  are 
firmly  connected  by  ligaments,  and  one  which  passes  from  the 
os  calcis  to  the  os  naviculare,  under  the  forepart  of  the  astra- 
galus, gives  effectual  support  to  that  bone. 

The  outside  of  the  foot,  formed  by  the  os  calcis,  os  cuboides, 
and  the  lesser  metatarsal  bone,  does  not  partake  much  of  the 
nature  of  an  arch ;  for  it  is  almost  flat.  As  the  internal  side 
forms  a  considerable  arch,  the  foot  is  to  be  considered  as 
possessing  a  double  convexity,  viz.  transversely,  as  well  as 
longitudinally.  2f 

The  great  toe,  from  its  internal  situation,  is  the  principal 
anterior  abutment  of  the  arch  on  the  internal  side  of  the  foot ; 
hence  its  great  importance. 

The  astragalus,  which  is  the  basis  of  the  tibia,  and  of  course 
pressed  by  half  of  the  weight  of  the  body  when  we  stand, 
appears  to  be  in  a  situation  which  is  very  oblique,  and  imper- 
fectly supported ;  and  accordingly  it  has  been  completely 
forced  from  its  position,  by  accidents  in  which  the  leg  has 
been  twisted  or  turned  inward,  and  the  foot  prevented  from 
turning  with  it.  It  is  probable  that  this  misfortune  would 
often  take  place  if  the  fibula  did  not  previously  yield,  as  in 
some  of  the  cases  of  fracture  of  that  bone  near  the  external 
ankle. 

One  great  object  of  this  peculiar  structure  is,  that  the  foot 
may  yield  in  cases  of  violent  and  sudden  pressure,  as  when  we 
jump  or  fall  upon  the  feet.  The  safety  of  the  foot,  and  the 
facility  of  its  ordinary  movement,  are  not  the  only  objects  of 
its  peculiar  structure,  but  concussion  of  the  whole  body,  and 
particularly  of  the  brain,  is  thereby  avoided  to  a  certain  de- 
gree. 

^his  may  be  inferred  from  the  fact  that  many  persons  suffer 
*  \=^  C-'  /  2fc+*  ** 

/,  &r« 


SESAMOID  BONES. EXTREMITIES  OF    THE  FffiTUS.          221 

violent  concussions,  in  consequence  of  falling  upon  other  parts 
of  the  body,  who  are  free  from  these  effects  when  they  fall 
upon  the  feet. 

The  Sesamoid  Bones 

Are  seldom  larger  than  half  a  pea.  They  are  most  commonly 
found  at  the  second  joint  of  the  thumb,  and  of  the  great  toe ; 
and  are  placed  in  pairs,  especially  at  the  great  toe,  between  the 
tendons  of  the  flexor  muscles  and  the  bones.*  In  these  situa- 
tions they  are  convex  externally,  and  on  their  internal  surfaces 
they  are  concave  and  covered  with  cartilage. 

They  are  also  sometimes  found  between  the  heads  of  the 
gastrocnemius  muscle  and  the  condyles  of  the  os  femoris. 

In  the  joints  of  the  thumb  and  toe  they  appear  to  be  very 
analogous  to  the  patella. 

— Besides  the  four  pair  of  sesamoid  bones  above  described  as 
belonging  to  the  skeleton,  viz.  two  upon  the  metacarpo-pha- 
langeal  articulation  of  each  thumb,  and  two  upon  the  corres- 
ponding joint  of  each  great  toe,  there  is  often  found  in  addition, 
one  upon  the  metacarpo-phalangeal  joint  of  the  little  finger, 
and  upon  the  corresponding  joint  in  the  foot.  There  is  one 
also  often  met  with  in  the  tendon  of  the  peroneus  longus  muscle, 
where  it  glides  through  the  groove  in  the  cuboid  bone.  Some- 
times they  are  found  in  the  tendons  that  wind  round  the  inner 
and  outer  malleolus  and  in  the  psoas  and  iliacus  where  they 
glide  over  the  body  of  the  os  pubis. — 

The  Extremities  of  the  Foetus. 

In  the  upper  extremity  the  clavicle  is  almost  perfect  at  birth  ; 
but  the  acromion  and  coronoid  processes  of  the  scapula,  as  well 
as  the  head,  are  in  a  cartilaginous  state. 

Both  ends  of  the  os  humeri  are  cartilaginous.  They  after- 
wards ossify  in  the  form  of  epiphyses,  and  are  united  to  the 
body  of  the  bone. 

The  two  bones  of  the  forearm  are  in  the  same  situation. 

*  They  are  properly  speaking  developed  in  the  tendons  of  these  muscles,  like 
the  patella  in  the  tendon  of  the  extensor  muscles  of  the  thigh.  The  patella 
itself  may  be  considered  a  specimen  of  a  sesamoid,  considering  its  mode  of 
development. — p. 

19* 


222  EXTREMITIES  OF  THE  FffiTUS. 

There  are  no  bones  of  the  carpus ;  but  in  their  situation  is  an 
equal  number  of  cartilages,  which  resemble  them  exactly. 
These  cartilages  are  separated  from  each  other,  by  synovia 
membranes,  as  the  bones  afterwards  are.  Each  of  them 
ossifies  from  a  single  point,  except  the  unciforme. 

The  metacarpal  bones,  and  the  first  bone  of  the  thumb 
have  cartilages  at  each  extremity,  which  afterwards  become 
epiphysis. 

The  bones  of  the  phalanges  are  likewise  cartilaginous  at  each 
extremity.  The  extremities  next  to  the  hand  are  epiphyses  ; 
but  it  is  probable  that  the  other  extremities  ossify  gradually 
from  their  centres.* 

In  the  lower  extremity,  the  head  and  neck,  and  two  tro- 
chanters  of  the  os  femoris  are  cartilaginous  and  form  three 
epiphyses. 

The  other  end  of  this  bone  is  also  cartilaginous,  and  consti- 
tutes but  one  epiphysis,  notwithstanding  its  size  ;  the  ossification 
commencing  in  the  centre. 

At  birth,  the  body  of  the  os  femoris  is  less  curved  than  it 
becomes  afterwards ;  and  the  angle  formed  by  the  neck  of  the 
bone  is  less  obtuse  than  in  the  adult. 

The  patella  is  entirely  cartilaginous  at  birth. 

The  two  extremities  of  the  tibia  and  fibula  are  also  cartilag- 
inous, and  become  epiphyses. 

The  astragalus  and  os  calcis  are  somewhat  ossified  within, 
and  have  a  large  portion  of  cartilage  exteriorly. 

In  place  of  the  other  bones  of  the  tarsus  there  are  cartilages 
of  their  precise  shape,  which  are  as  distinct  from  each  other  as 
the  future  bones  are. 

The  state  of  the  metatarsal  bones,  and  the  phalanges  of  the 
toes,  resembles  that  of  the  bones  of  the  hand.f 

*  See  Nesbit's  Osteology,  page  126. 

f  Volehn  Koyter,  a  disciple  of  Fallopius,  has  given  to  the  profession  one  of 
the  best  accounts  of  Osteogeny,  according  to  Lassus. — H. 


PART   II. 

SYNDESMOLOGY. 

CHAPTER  III. 

GENERAL  ANATOMY  OF   THE    LIGAMENTOUS,  FIBROUS,  OR 
DESMOID  TISSUE. 

Of  the  ligaments  aud  membranes  which  connect  the  different  parts  of  the  body 
to  each  other— Of  the  articular  cartilage— Fibro-cartilages— Synovial  cap- 
sules, and  particular  articulations. 

THE  tendons  and  the  strong  membranes  connected  with  them 
called  aponeuroses,  the  fascia  which  bind  down  some  of  the 
muscles  and  afford  an  origin  to  many  of  their  fibres,  and  the 
membranes  which  confine  the  tendons,  appear  to  be  composed 
of  the  same  substance. 

— Notwithstanding  some  slight  shades  of  difference  which 
exist  in  the  physical  and  chemical  composition  of  these  different 
parts,  they  are  all  now  included  with  the  periosteum,  perichon- 
drium,  dura  mater,  sclerotic  coat  of  the  eye,  &c.,  under  the 
general  head  of  ligamentous,  fibrous,  or  desmoid  tissue.* 
This  tissue  is  sometimes  called,  from  the  whiteness  of  its 
appearance,  the  albugineous  tissue.  It  is  spread  very  gene- 
rally throughout  the  body,  and  is  found  wherever  extraordinary 
strength  and  resistance  is  required,  without  elasticity  or  muscu- 
lar contraction.  It  has  been  called  ligamentous  or  desmoid, 
from  its  fastening  together  the  bones  and  cartilages,  as  in  the 
ligaments  proper,  and  from  binding  down  the  muscles  so  as  to 
preserve  the  symmetry  of  the  limbs,  in  the  form  of  fascia  and 

*  The  term  ligament  is  frequently,  though  not  with  exact  propriety  applied  to 
the  duplicatures  of  serous  membranes,  which  are  attached  to  and  assist  in  sup- 
porting different  viscera,  as  the  liver,  bladder,  uterus,  &c.,  since  these  do  not 
belong  to  the  fibrous  or  desmoid  tissue. — p. 


2'24  FIBROUS    TISSUE. 

aponeurosis,  and  from  fastening  the  tendons  in  their  grooves 
in  the  form  of  their  theca's  or  sheaths.  The  term  fibrous  was 
applied  to  it  by  Bichat,  (though  its  elements  are  dissimilar  to 
muscular  fibre,)  in  consequence  of  its  performing  the  office  of 
bands  or  chords,  and  being  composed  essentially  of  firm  in- 
elastic threads,  or  albuminous  fibres.  These  fibres  crossing 
each  other  in  various  directions  and  woven  densely  together, 
with  some  intervening  cellular  tissue,  form  the  aponeuroses, 
fascia?,  sheaths,  articular  capsules,  periosteum,  dura  mater, 
and  tunica  albuginea ;  arranged  longitudinally,  they  form  the 
tendons  of  the  muscles  and  the  straight  ligaments  of  the  joints. 
The  tendons,  by  a  little  dissection,  may  be  spread  out  into  a 
membrane,  and  in  some  parts  of  the  body  we  see  them  naturally 
unfolding  themselves  to  form  an  aponeurosis. 
— Between  all  these  different  parts  there  is  more  or  less  con- 
nexion. The  tendons  are  inserted  upon  the  bones  only  through 
the  intermedium  of  the  periosteum,  by  which  the  bones  are 
covered.  The  aponeuroses  are  connected  with  the  periosteum 
by  the  fasciae  which  they  send  down  between  the  muscles. 
The  ligaments  and  periosteum  are  directly  continuous,  and 
the  dura  mater,  as  it  sends  out  processes  around  the  nerves, 
becomes  continuous  with  the  periosteum  that  lines  the  foramina 
of  the  bones,  through  which  the  nerves  pass.  Bichat,  con- 
sidered the  periosteum  the  source  and  centre  of  this  system  ; 
Bonn,  of  Amsterdam,  as  well  as  Clarus,  believed  the  aponeu- 
roses investing  the  limbs  to  be  the  centre ; — an  opinion  more 
venerable  than  either  of  these,  that  of  the  Arabian  anatomists, 
fixed  it  in  the  dura  mater.  But,  in  truth  there  is  no  proper 
centre.  In  many  parts,  there  is  a  fibrous  tissue  isolated  from 
the  rest,  as  the  investing  coat  of  the  spleen  and  kidneys,  and 
the  fibrous  portion  of  the  pericardium. 

— The  fibrous  tissue  in  all  parts  of  the  body  is  continuous,  at 
its  surfaces  and  margins,  with  the  common  cellular  tissue,  and 
in  many  parts  we  find  it,  especially  in  the  aponeuroses  and 
fasciae,  degenerating  insensibly  into  it.  There  appears  in  fact 
to  be  a  close  relationship  between  these  two  tissues ;  in  its 
development  in  the  foetus,  it  first  appears  as  a  soft,  flexible, 


FIBROUS  TISSUE.  225 

i 

extensible,  homogeneous  tissue,  resembling  much  the  cellular, 
and  presents  no  appearance  of  fibres,  till  near  the  period  of 
birth.  As  life  advances  it  becomes  more  hard,  soliti*^  and 
yellow,  and  in  extreme  old  age  presents  much  rigidity,  and  is 
occasionally  even  converted  into  bone.  When  macerated  in 
water,  or  imbued  with  fluids,  as  in  scrofulous  inflammation  of 
the  joints,  it  presents  a  pulpy,  spongy  appearance,  in  the  cells 
of  which  the  fluid  is  contained.  If  the  maceration  is  carried 
only  to  a  limited  extent,  the  fibres  will  separate  into  filaments, 
as  delicate  as  those  of  the  silk  worm  ;  but  by  prolonged  mace- 
ration these  filaments  themselves  disappear  in  the  cellular 
mass.  Mascagni,  believed  these  fibres  were  lymphatics  en- 
closed in  a  vascular  web.  Beclard,  that  they  were  nothing  but 
condensed  cellular  tissue.  Isenflam,  that  it  was  cellular  tissue, 
with  the  walls  imbued  and  the  cells  filled  with  gluten  and 
albumen,  and  more  or  less  in  the  advance  of  life  with  earthy 
matter;  an  opinion  which  seems  to  accord  with  the  different 
phases  which  the  tissue  presents.  Chaussier  and  Bichat,  con- 
sidered the  fibre  as  primitive  and  peculiar,  and  that  maceration 
only  brought  into  view  the  cellular  tissue  which  connected  the 
fibres  together. 

— However  this  may  be,  and  it  is  a  question  not  yet  decided, 
in  the  form  in  which  it  presents  itself  to  study,  it  differs  in 
many  respects  from  cellular  tissue.  It  is  not  elastic  or  yielding 
to  the  application  of  sudden  force  as  the  latter ;  the  fibres  will 
break  or  tear  up  at  their  bony  attachment,  but  cannot  be 
stretched  or  strained  in  the  proper  sense  of  the  word.  But 
when  the  force  is  gradually  applied,  as  by  the  accumulation  of 
a  fluid  in  a  joint,  they  yield  to  receive  it,  by  a  sort  of  interstitial 
expansion  or  growth,  and  retract  in  the  same  gradual  manner, 
when  the  distending  power  is  removed.  Fibrous  tissue  contains 
but  little  adipose  matter,  and  is  affected  only  to  a  slight  extent 
in  anasarca. 

— The  labors  of  the  microscopists  have  recently  confirmed  the 
opinion  of  Chaussier  and  Bichat. 

— They  have  shown  fibrous  tissue  to  consist  of  fine  transparent 
undulating  cylindrical  filaments,  about  i^00  part  of  an  inch  in 


226  FIBROUS  TISSUE. 

diameter.  They  are  generally  collected  in  minute  fasciculi, 
from  5^00  to  T0^g  and  these  again  into  larger  fasciculi  ^  to  ^  of 
an  inch  wide,  the  filaments  of  which  are  held  together,  by  a  firm 
structureless  amorphous  substance,  which  has  received  the  name 
of  cytoblastema.  Under  the  microscope,  the  elementary  struct- 
ure of  the  cellular,  fibrous  and  fibro-cellular  tissues,  appear  to  be 
the  same.  Their  anatomical  ^differences  depending  on  the  mode 
in  which  their  elementary  fibres  are  put  together.  In  fibrous 
tissue  the  undulating  primitive  filaments  are  arranged  side  by  side 
into  fasciculi,  which  differ  from  those  of  cellular  tissue  in  being 
much  larger,  more  dense  and  more  opaque  and  in  being  straight 
instead  of  flexuous.  Their  whiteness  and  strength,  depend 
upon  the  compact  parallel  disposition  of  the  compound  fila- 
ments ;  and  their  slight  amount  of  elasticity  is  owing  to  the 
absence*  of  sinuosity  in  the  arrangement  of  the  compound 
fasciculi.  According  to  the  manner  in  which  these  fasciculi  or 
fibres  are  arranged  and  combined,  we  have  either  the  mem- 
branous or  fascicular  form  of  fibrous  tissue  as  has  been  above 
explained.  Cellular  membrane  in  a  more  or  less  condensed 
state,  is  found  in  general  intermixed  to  a  greater  or  less  extent, 
with  the  fibrous  fasciculi. 


The  Ligaments  of  the  Joints, 

— Are  all  divided  into  the  capsular  or  bag-like,  and  into  funicu- 
lar, or  cords. 

— The  capsular,  or  fibrous  bags,  of  greater  or  less  thickness, 
open  at  both  ends,  into  which  the  heads  of  the  bones  forming 
the  respective  joints  are  thrust,  and  round  the  necks  of  which 
it  is  closely  inserted,  where  they  are  continuous  with  the  peri- 
osteum of  the  bones.  In  very  many  of  the  joints  the  capsules 
are  imperfect  in  some  part  of  their  periphery,  and  in  others 
are  represented  only  by  a  few  scattered  fibres.  The  hip  and 
shoulder  joint  furnish  the  best  specimen  of  a  perfect  capsule. 
— The  funicular  ligaments  are  cords,  flat,  round,  or  oval, 
intended  to  give  a  side  support  to  the  joints,  and  constitute 
the  lateral  ligaments.  These  are  placed,  some  within,  some- 


FIBROUS    TISSUE.  227 

without,  and   some   in   the  very  thickness  of  the  capsular  liga- 
ment.— 

They  consist  of  fibres  which  are  flexible  but  extrefnely 
strong,  and  in  general  have  but  little  elasticity ;  their  surfaces 
are  smooth  and  polished ;  their  color  is  whitish  and  silver- 
like. 

The  vessels  which  enter  into  their  composition  do  not  com- 
monly carry  red  blood  ;  and  although  it  seems  certain  that 
they  must  have  nerves,  many  very  expert  anatomists  have  declar- 
ed that  no  nerves  could  be  traced  into  them. 
— A  branch  of  the  fourth  cranial  nerve,  has  however  been 
found  distributed  in  the  dura  mater.  Blood  vessels  abound  in 
the  periosteum,  but  they  merely  divide  in  that  membrane,  so 
as  to  enter  the  bone  at  a  great  number  of  points,  as  has  been 
before  observed. — 

In  a  healthy  state,  they  are  entirely  void   of  sensibility,  and  ^ 
can    be   cut   and    punctured,  or   corroded    with    caustic  appli- 
cations, without    pain.      When    inflamed    they    are   extremely 
painful. 

The  ligaments  which  connect  the  different  bones  to  each 
other,  have  a  very  strong  resemblance  to  these  tendinous  parts, 
not  only  in  their  structure  but  in  their  qualities  also.  Many  of 
them  appear  rather  more  firm  in  their  texture  and  more  vascular. 
Their  vessels  are  also  larger:  their  color  sometimes  inclines  to  a 
dull  white,  and  when  examined  chemically,  they  appear  to 
differ,  in  some  respects,  from  tendons.  t 

They  agree,  however,  with  the  tendinous  parts  as  to  their 
insensibility  in  a  sound  state,  and  the  extreme  pain  which  occurs 
when  they  are  inflamed.  No  nerves  have  been  traced  into  their 
structure. 

Notwithstanding  the  ordinary  insensibility  of  these  parts,  it 
was  asserted  by  M.  Bichat  that  several  animals  who  seem  to 
suffer  no  pain  from  cutting,  puncturing,  or  corroding  the  liga-  \ 
ments  of  their  joints,  appeared  to  be  in  great  agony  when 
these  parts  were  violently  stretched  or  twisted  ;  and  he  de- 
clared this  to  be  the  case  when  all  the  nerves  which  passed 
over  the  ligaments,  and  could  have  been  affected  by  the 


228  FIBROUS    TISSUE. 

process,  were  cut  away.  He  explained  by  this  the  pain  which 
sometimes  occurs  instantaneously  in  sprains,  in  the  reduction  of 
luxations,  and  in  other  analogous  processes. 

The  ultimate  structure  of  these  parts  is,  perhaps,  not  perfectly 
understood. 

An  anatomist  of  the  highest  authority,  Haller,  appears  to 
have  considered  them  as  fqrmed  of  membrane,  while  a  late 
writer,  who  has  paid  great  attention  to  the  subject,  and  is  also 
of  high  authority,  M.  Bichat,  has  satisfied  himself  that  their 
structure  is  essentially  fibrous. 

If  a  tendon,  or  portion  of  tendinous  membrane,  be  spread 
out,  or  forcibly  extended,  in  a  direction  which  is  transverse 
with  respect  to  its  fibres,  it  will  seem  to  be  converted  into  a 
fine  membrane,  and  the  fibres  will  disappear  to  the  naked  eye. 
The  same  circumstances  will  occur  when  a  ligament  is  treated 
in  a  similar  way ;  but  much  more  force  is  required. 

Thus  constructed,  these  parts  are  perfectly  passive  portions  of 
the  animal  fabric,  and  have  no  more  power  of  motion  than  the 
bones  with  which  many  of  them  are  connected. 

But  notwithstanding  their  ordinary  insensibility,  they  often 
induce  a  general  violent  affection  of  the  system  when  they  are 
diseased.  A  high  degree  of  fever,  as  well  as  severe  pain, 
attends  their  acute  inflammations  ;  and  hectical  symptoms,  in 
their  greatest  extent,  are  often  induced  by  their  suppurations. 

There  is  another  circumstance  in  their  history  which  is  very 
difficult  to  reconcile  with  their  ordinary  insensibility.  They  are 
the  most  common  seats  of  gouty  painful  affections. 

In  these  cases,  pain  does  not  seem  to  be  the  simple  effect  of 
inflammation  :  it  often  occurs  as  the  first  symptom  of  the  dis- 
ease ;  it  frequently  exists  with  great  violence  for  a  short  time  and 
goes  off  without  inflammation,  and  it  is  frequently  vicarious  with 
affections  of  the  most  sensible  and  irritable  parts,  -v 

Parts  of  a  tendinous  and  ligamentous  structure  do  not  appear 
retentive  of  life,  but  lose  their  animation  very  readily,  in  conse- 
quence of  the  inflammation  and  other  circumstances  which  attend 
wounds. 

When  thus  deprived  of  life,  they  retain  their  usual  appear- 
-         %#^, 

^^  v",   ***•?     *)  ts*J**r»jL.&£^    ft>Cs&^ 

+-*£<,    ~^f' 

\.    sfi&^-^tf  —    jffif^ 

'  •&*  "*^&j    £fT jtffa,    ev^^V 


YELLOW  ELASTIC    LIGAMENTOUS  TISSUE. 


229 


ance  and  their  texture  a  long  time.  The  dead  parts  separate 
from  the  living  in  large  portions,  in  a  way  which  has  a  con- 
siderable analogy  with  the  exfoliation  of  bones. 

The  tendons  and  their  expansions,  and  the  various  fasciae, 
have  the  same  chemical  composition.  If  boiled  a  long  time, 
they  dissolve  completely,  and  form  the  substance  called  by 
chemists  gelatine,  or  pure  glue. 

The  ligaments  differ  from  them  in  some  respects.  When 
boiled  they  yield  a  portion  of  gelatine,  and  do  not  dissolve 
entirely ;  but  are  said  to  retain  their  form  and  even  their 
strength,  after  a  very  long  boiling.  The  composition  of  the 
part  so  insoluble  in  water,  has  not  yet  been  ascertained. 

Of  the   Yellow  Elastic  Ligamentous   Tissue. 

Fig.  49.*  — This  is  a   modification  of 

the  common  ligamentous  tis- 
sue,*which  though  not  usual- 
ly treated  apart,  differs  from 
it  in  many  essential  particu- 
lars. It  contains,  according 
to  the  younger  Girard,  some 
fibrine  in  its  composition  ;  it 
is  eminently  elastic,  and  is 
placed  to  give  resistance  and 
support  to  parts,  where  in 
other  animals,  we  meet  with 
muscular  fibres,  for  which  it  is  in  some  sort  a  substitute.  In  some 
situations  it  is  of  a  deep  yellow  color,  and  rarely  presents  the 
silvery  aspect  of  the  common  tissue.  It  forms  the  middle  coat 
of  the  arteries,  the  ligaments  between  the  bridges  of  the  verte- 
brae, the  ligamentum  nucha3  in  quadrupeds  with  heavy  pen- 
dant heads,  the  elastic  involucrum  oj  the  corpus  cavernosum 
and  spongiosum  penis  in  the  male,  of  the  clitoris  in  the  female, 

*  Reticulate  elastic  tissue  from  the  ligamentum  nuchae  of  the  horse  magnified 
to  200  diameters  (from  Gerber).     a.  Loosened  elastic  tissue  with  the  meshes 
opened,    b.  Elastic  tissue  in  its  natural  condition,  the  meshes  close  j  the  fibres 
being  disposed  in  lines  and  layers,  parallel  to  one  another. 
20 


230 


FIBRO-LIGAMENTOUS    TISSUE. 


/  and  the  elastic  covering  of  the  spleen ;  it  is  found  in  the  rami- 
fications of  the  bronchia,  in  various  parts  of  the  eye  ball,  and  in 
the  ligaments  of  the  larynx  and  os  hyoides  including  the  vocal 
chords ;  we  might  also  add,  the  elastic  membrane  of  the  nose 
and  ear,  which  are  more  allied  to  it,  than  to  cartilage,  though 
they  are  called  membraniform  cartilage.  This  yellow  elastic 
tissue,  (tissue  jaune)  unlike  otfcer  ligamentous  tissue,  yields  no 
gelatine  on  boiling.  It  resists  decomposition  for  a  very  long 
time,  either  by  maceration,  putrefaction,  or  digestion  ;  it  becomes 
brown  and  transparent  on  drying,  but  not  brittle  like  cartilage. 
Fig.  50.*  When  examined  with  the  mi- 

croscope, it  is  found  to  bear  in 
the  arrangement  of  its  fibres 
a  strong  resemblance  to  a 
net  work  of  capillary  vessels. 
Its  fibres  are  rigid,  prismatic 
in  form  and  about  the  ^g 
part  of  a  line  in  diameter, 
highly  elastic  and  interlaced 
with  each  other  at  all  angles ; 
its  embryonic  cells  are  elon- 
gated and  mixed  with  the 
fibres.  If  injured  it  is  very 
imperfectly  reproduced ;  a  dense  fibrous  tissue  being  substi- 
tuted in  its  place.  It  is  very  sparingly  supplied  with  blood- 
vessels. 


Of  the  Fibro-cartilaginous  or  Ligamento-cartilaginous  Tissue. 

— There  is  another  variety  of  the  desmoid  tissue,  which  holds 
a  middle  station  between  ligament  and  cartilage,  partakes 
partly  of  the  nature  of  both,  and  has  been  treated  of  by  Bichat 
as  a  distinct  tissue  under  this  compound  name.  Vesalius  and 

*  Elastic  tissue  from  the  middle  fibrous  coat  of  the  aorta  of  the  ox  magnified 
300  diameters.  The  intertangled  fibres,  and  elongated  cells  are  well  shown 
(from  Gerber).  These  fibres,  according  to  Henle,  are  contractile,  and  resemble 
.somewhat  the  muscular  fibres  of  the  stomach. 


FIBRO-LIGAMENTOUS    TISSUE.  .         231 

Morgagni,  called  them  cartilaginous  ligaments ;  Haase,  mixed 
ligaments.  Like  ligaments,  they  present  a  well  marked  fibrous 
appearance,  and  are  strong  and  resisting.  Like  cartilages, 
they  are  white,  very  dense  and  elastic.  Beclard  divides  them 
into  the  temporary  and  permanent.* 

— The  temporary,  are  those  which  pass  regularly  and  at 
determined  periods  to  the  state  of  ossification,  and  are  developed 
in  the  midst  of  the  ligaments  and  tendons,  as  the  patella  and 
sesamoid  bones. 

— The  permanent  are  of  several  kinds.  1.  Those  which  are 
free  at  both  these  surfaces,  and  are  lined  by  the  synovial  mem- 
brane. These  constitute  the  interarticular  or  meniscous  carti- 
lages, (menisci,)  and  are  attached  at  their  outer  surface  to  the 
inner  face  of  the  capsular  ligament.  They  are  found  in  the 
knee,  maxillary,  clavicular,  and  lower  ulnar  articulations. 
2.  Those  which  are  adherent  by  one  of  their  surfaces ;  these 
are  found  whenever  the  fibrous  tissue  is  subjected  to  habitual 
friction  by  the  tendons,  as  in  the  different  grooves,  through 
which  they  play,  or  upon  the  sides  of  the  ligaments  or  carti- 
lages, against  which  they  rub  ;  the  periosteum,  or  whatever 
fibrous  membrane  it  may  be,  first  becomes  thickened  and  then 
converted  into  a  semicartilage.  It  also  exists  in  the  fibrous 
rings,  placed  at  the  margin  of  the  glenoid  and  cotyloid  cavities 
for  the  purpose  of  deepening  their  sockets.  3.  Those  adherent 
by  both  surfaces.  These  are  found  between  the  bodies  of  the 
vertebrae  and  the  pubic  bones. 

— The  accidental  production  of  this  tissue  is  by  no  means 
uncommon  ;  it  is  found  occasionally  in  the  cavities  of  fractures 
forming  false  joints,  in  the  tubercular  cavities  of  the  lungs,  in 
the  uterus,  ovaries,  etc. 

*  Bichat  considered  the  elastic  cartilaginous  membranes  of  the  nose,  ear,  and 
trachea,  as  belonging  to  this  division  of  the  tissues,  but  they  certainly  have  a 
closer  affinity  to  the  yellow  elastic  fibrous  tissue. — p. 


232  OF    ARTICULATIONS. 


CHAPTER   IV. 

A  GENERAL  ACCOUNT  OF  ARTICULATIONS,  AND  OF 


Of  Articulations. 

THOSE  surfaces  of  bones  which  form  the  movable  articula- 
tions are  covered  with  cartilaginous  matter  which  has  been 
already  described.* 

—  In  many  of  the  immovable  articulations,  as  the  sacro-iliac 
symphysis  for  instance,  a  thin  lamen  of  cartilaginous  matter, 
with  all  the  other  appurtenances  of  joints,  are  likewise  met 
with.  The  connexion  between  the  articular  cartilage  and  the 
bones  is  strong,  but  its  nature  is  not  well  known.  None  of 
the  vessels  of  the  bone  pass  into  the  cartilage,  but  terminate  in 
its  immediate  neighborhood.  Gerdy,  (page  29)  considers  it 
a  secretion  from  these  vessels,  and  that  its  formation  is  like 
that  of  the  cuticle,  from  the  vessels  of  the  skin.  This,  however, 
is  but  a  mere  opinion,  unsustained  by  proof.  It  presents  the 
appearance  of  a  couch  of  white  wax  spread  over  the  end  of 
the  bones,  though  it  is  composed  of  vertical  fibres  like  the  frill 
of  velvet,  so  crowded  together  as  to  leave  no  sensible  interval 
between  them,  and  presenting  a  free  extremity  to  the  cavity  of 
the  joint.  The  cartilages  terminate  insensibly  at  their  circum- 
ference on  the  surface  of  the  bone.  On  the  heads  of  the  bones 
they  are  thicker  at  the  central  part,  than  at  their  circumference  ; 
in  the  corresponding  socket,  the  cartilaginous  coating  is  thickest 
at  the  margin,  and  sometimes  spreads  out  into  a  sort  of  carti- 
laginous rim.  — 

—  On  the  formation  of  the  epiphysis  of  the  long  bones,  and  its 
covering  cartilage.  —  In  the  foetus  and  young  subject,  there  is 
no  distinction  between  the  cartilage  that  is  to  become  the  bone 
of  the  epiphysis  and  that  which  is  to  remain  as  articular  carti- 

*  See  page  36. 


FORMATION  OF  THE  EPIPHYSIS  OF    LONG  BONE.  233 

• 

lage.  In  my  preparations  alluded  to,  page  236,  a  careful  dis- 
section shows  branches  running  from  the  zone  of  vessels  across 
the  head  of  the  bone  isolating  the  articular  cartilage  froni  the 
epiphysal.  These  branches  have  beds  of  bone  formed  round 
them,  communicate  freely  with  the  vessels  of  the  epiphysis, 
but  appear  to  send  no  branches  towards  the  free  surface  of  the 
articular  cartilage.  The  portion  of  the  articular  cartilage 
immediately  overlaying  them,  is  ,  however  ,  more  tough  and 
periosteal  in  its  character,  than  that  on  the  free  surface  of  the 
cartilage,  and  has  been,  though  not  with  exact  propriety, 
described  by  Mr.  Listen,  as  cellular  tissue  connecting  the  carti- 
lage and  epiphysis.  It  is  well  known  that  in  young  subjects,  the 
articular  cartilage  is  thick,  and  fhe  compact  layer  of  the  epi- 
physis below  it  thin  and  fragile  ;  while  in  old  persons  the  com- 
pact layer  of  the  epiphysis  is  thick  and  strong,  and  the  cartilage 
covering  is  thin,  rigid,  and  so  firmly  united  to  the  bone  below, 
as  to  be  with  difficulty  removed  from  it  by  the  ordinary  process 
of  cleaning.  It  would  seem  from  this,  that  .while  the  cartilage 
gets  its  nutritive  fluids  by  imbibition  from  the  epiphysal  vessels 
and  the  marginal  zone,  some  change  is  effected  by  their  passage 
into  its  structure  during  the  progress  of  life,  by  which  the  inner 
portions  of  the  articular  cartilage  is  converted  into  bone. 
Though  in  the  healthy  state  no  vessels  can  be  injected  in  carti- 
lage, in  some  diseases  of  the  joints  blood-vessels  and  granula- 
tions may  shoot  up  from  the  bone  below  into  the  place  of  the 
cartilage.  —  It  has  been  most  probably  in  cases  of  this  de- 
scription, that  the  appearance  of  vascularity  in  the  cartilages 
has  been  observed;  that  of  Mr.  Liston,  detailed  in  a  late  num- 
ber of  the  medico-chirurgical  transactions  was  from  a  diseased 


The  bones  are  retained  in  their  relative  situations  by  liga- 
ments, such  as  have  been  lately  mentioned,  which  are  exterior 
to  the  cavities  of  the  articulations,  and  placed  in  such  situa- 
tions that  they  permit  the  motions  the  joints  are  calculated 
to  perform,  while  they  keep  the  respective  bones  in  their 
proper  places. 

20* 


234  SYNOVFAL    CAPSULES. 

Of  the  Synovial  Capsules. 

•< — The  synovial  capsules  are  formed  of  an  extremely  thin 
transparent,  double  reflected  tissue,  the  vessels  of  which  circu- 
late in  the  healthy  state  only  the  serous  portions  of  the  blood, 
and  which,  though  erected  into  a  distinct  tissue  or  system  by 
Bichat,  under  the  name  of  synovial,  is  now  generally  considered 
as  forming  only  a  part  of  th£  general  serous  tissue,  which  it 
closely  resembles  in  structure,  and  with  which  it  intimately 
sympathizes  in  disease.  They  are  of  three  kinds :  1st.  Those 
which  line  the  inner  surface  of  the  ligaments  of  the  joints,  and 
are  reflected  over  the  surfaces  of  the  articular  cartilages.  These 
are  called  the  articular  synovial  cartilages.  2d.  Those  which 
are  placed  between  the  tendons  of  the  muscles,  and  the  bones 
and  cartilages  against  which  the  tendons  rub.  These  are  called 
burscE  mucoscs.  3d.  Those  which  are  placed  between  the* skin 
and  the  bones,  tendons,  or  other  hard  parts,  over  which  it  per- 
forms frequent  and  extensive  movements.  These  are  called  the 
subcutaneous  synovial  capsules. — 

Of  the  Articular  Synovial  Capsules. 

They  are  invested  in  a  particular  manner  by  a  thin  delicate 
membrane,  which  in  some  joints,  as  those  of  the  hip  and 
shoulder,  seems  to  be  the  internal  lamina  of  a  stronger  liga- 
ment called  the  capsular ;  and,  in  other  joints,  the  knee,  for 
example,  appears  to  be  independent  of  any  other  structure. 
In  each  case,  this  synovial  membrane,  as  it  has  lately  been 
called,  forms  a  complete  sac  or  bag  which  covers  the  articular 
surface  of  one  bone,  and  is  reflected  from  it  to  the  correspond- 
ing surface  of  the  other ;  adhering  firmly  to  each  of  the 
articulating  surfaces,  and  extending  loosely  from  the  margin  of 
one  surface  to  that  of  the  other. 

In  the  distribution  it  supplies  the  place  of  perichondrium  to 
the  cartilages,  and  of  periosteum  to  those  surfaces  of  bone  with 
which  it  is  connected. 

It  seems  greatly  to  resemble  the  membranes  which  line  the 

-  '    ;4&**v. 


-U^2  <V"~-  -/ 


SYNOVIAL    CAPSULES.  235 

abdomen  and  thorax,  and  invests  the  parts  contained  in  these 
cavities  ;  and  like  them  it  may  be  termed  a  reflected  membrane. 

It  is  thin  and  very  flexible,  but  dense  and  strong.        ; 

It  secretes,  or  effuses  from  its  surface,  a  liquor,  called  synovia  ; 
which  is  particularly  calculated  to  lubricate  parts  that  move 
upon  each  other,  x* 

The  fluid  is  nearly  transparent :  it'  has  the  consistence  of  a 
thin^yjuj^and  is  very  tenacious  or  ropy.  It  mixes  with  cold 
water,  and,  when  heated,  becomes  milky,  and  deposits  some 
pellicles  without  losing  its  viscidity.  It  appears  to  be  composed 
of  eighty  parts  in  one  hundred  of  water  ;  above  eleven  parts  of 
fibrous  matter;  and  between  four  and  five  parts  of  albumen. 
It  also  contains  a  small  portion  of  soda,  of  muriate  of  soda,  and 
of  phosphate  of  lime.  t 

There  are  in  many  of  the  joints  masses  of  fat  which  appear 
to  project  into  the  cavity,  but  are  exterior  to  the  synovial 
membrane,  and  covered  by  it ;  as  the  viscera  in  the  abdomen 
are  covered  by  the  peritoneum. 

They  are  generally  situated  so  as  to  be  pressed  gently,  but 
not  bruised,  by  the  motions  of  the  bones. 

In  some  joints,  they  appear  like  portions  of  the  common 
adipose  membrane  ;  in  others,  they  appear  more  vascular,  and 
have  a  number  of  blood-vessels  spread  upon  them.  Small 
processes  often  project  from  their  side  like  fringe. 

These  masses  have  been  considered  as  synovial  glands ;  but 
they  do  not  appear  like  glands  ;  and  it  is  probable  that  the 
synovia  is  secreted  by  the  whole  internal  surface  of  the  mem- 
brane.* 

,       The  synovial  membrane,  like  the   other   parts   of  joints,  is 
'   insensible  in  a  sound  state,  but  extremely  painful  when  inflamed. 
The  synovia,  which  is  secreted,  during  the  inflammation  of  this 
membrane,  has  a  purulent  appearance. 

— For  the  sake  of  facility  in  description  it  is  common  among 
anatomists,  without  admitting  or  denying  the  fact,  to  consider 

*  Clopton  Havers,  ignorant  that  the  synovia  was  derived  by  a  sort  of  perspira- 
.  lion  from  the  inner  surface  of  this  membrane,  supposed  it  to  be  secreted  by  these 
masses  of  adipose  matter,  which  are  still  known,  in  perpetuation  of  his  mistake, 
as  Havers'  glands.— T. 


-  f^    JL&. 

'tl^C**  - 


\ 

236  SYNOVIAL    CAPSULES. 

the  synovial  membrane  as  passing  over  the  face  of  the  articular 
cartilages  ;  it  has  however  long  been  a  question  among  anato- 
mists and  surgeons,  whether  such  be  really   the  case.     It  can 
only  be  traced   by  the  knife  as  far  as  the  circumference  of  the 
cartilages,  nor  can  vessels  by  any  means  in  the  healthy  state 
be  injected   in  it  beyond  this  point.     If  it  exist  upon  the  carti- 
lages, it  is  certainly  so  modifieq^  as  not  to  be  recognizable.     It  is 
asserted  by  Mr.   Toynbee*   that   it   covers   the   cartilage  as  a 
vascular  membrane  only  in  the  early  periods  of  foetal  life — and 
that  towards  the  period  of  birth  the  sub-synovial  vessels,  gradu- 
ally recede  from  the  surface  of  the  articular  cartilage  and  form 
a  zone  around  its  margin  ;  a   change  somewhat  like  that  which 
takes    place   in    the    membrana     pupillaris.       I     have    several 
minutely  injected  preparations  of  the  joints  taken  from  young 
subjects,  which   show   this   zone   of  vessels,  arranged  in  loops 
somewhat  like   the   mesenteric  arches,  around  the  beveled  cir- 
cumference of  the  cartilage,  which  are  strongly  confirmatory  of 
this    opinion.      But   whether   the   synovial    membrane  recedes 
with   these  vessels,  or  becomes  so    altered   in   character  as    to 
form   a  smooth  insensitive  covering  to  the  cartilage  has  not  yet 
been  determined.     An    amputation  at  the  knee  joint  which  I 
performed  at  the  Philadelphia  Hospital,f  before  the  class  of  the 
Jefferson  Medical  College,  gave  me  an  opportunity  of  observing 
the  changes   daily,  that  are   produced  by  morbid  causes  in  the 
cartilages  of  the  joints.     From   the  diseased   condition   of  the 
integuments  of  the  leg,  there  was  a  scantiness  of  flap  for  cover- 
ing the  stump,  which  left  the  condyles  partly  exposed  to  view. 
— From  round  the  margin  of  the  cartilage  and  the    place  of 
attachment   of    the   crucial  ligaments,   in    front   of  which    the 
synovial  membrane  passes,  there  was  in  the  course  of  a  fort- 
night inflammation,  secretion  and  a   vigorous  growth  of  granu- 
lations.    On  the  surface  of  the  cartilage  of  the  condyles  there 
appeared  to  be  up  to  this  time  the  slightest  change ;  it  preserved 
its   polished   shining  aspect    and  was   totally    insensible  to   the 
contact  of  an  instrument.     In  the  course  of  a  few  days  more  it 

*  Memoir  on  the  non  vascular  tissues,  Phil.  Trans.  1841. 
f  For  the  details  of  this  case  see  Pancoast's  Operative  Surgery,  2d  Edit.  p. 
169. 


BURS.E    MUCOS,E.  237 

lost  its  polish,  became  soft  and  pulpy,  like  a  joint  exposed  to 
maceration  in  a  dissecting  room,  and  melted  off,  flake  after  flake, 
till  the  compact  layer  of  bone  covering  the  cells  of  the  epfphysis 
below  was  exposed  to  view.  This  layer  was  at  first  dark 
colored,  but  soon  became  red  and  sensitive  to  the  touch. 
Small  firm  whitish  conical  elevations,  appeared  over  its  surface; 
these  grew  by  degrees  into  strong  and  healthy  granulations,  to 
which  the  inner  face  of  the  flaps,  at  the  end  of  six  weeks  were 
firmly  connected,  leaving  the  patient  a  solid  and  serviceable 
stump,  upon  which  she  is  able  to  bear  her  weight  with  the 
ordinary  wooden  support.  The  patient  suffered  none  of  the 
constitutional  irritation  common  to  synovial  inflammation  and 
it  would  be  difficult  to  believe  from  the  progress  of  this  case, 
and  analogous  ones  reported  by  other  surgeons,  either  that  the 
synovial  membranes  are  spread  over  the  cartilages  of  joints, 
or  that  the  cartilages  themselves  are  vascular. 

Of  BurscE  Mucosa. 

There  are  certain  membranous  cavities  called  bursae  mucosae 
which  are  found  between,  tendons  and  bones,  near  the  joints, 
and  in  other  places  also,  which  have  so  strong  a  resemblance  to 
the  synovial  membrane,  and  are  so  intimately  connected  with 
some  of  the  articulations,  that  they  ought  now  to  be  mentioned. 

They  are  formed  of  a  thin  dense  membrane,  and  are  attached 
to  the  surrounding  parts  by  cellular  substance  ;  they  contain 
a  fluid  like  the  synovia  ;  and  sometimes  there  are  masses  of 
fat,  which,  although  exterior  to  them,  appear  to  project  into 
their  cavities. 

There  is,  commonly,  a  thin  cartilage,  or  tough  membrane, 
between  them  and  the  bone  on  which  they  are  placed. 

They  often  communicate  with  the  cavities  of  joints,  without 
inducing  any  change  in  the  state  of  the  part. 

As  they  are  always  situated  between  parts  that  move  upon 
each  other,  there  is  the  greatest  reason  to  believe  that  they  are 
intended  to  lessen  friction.* 

*  For  further  information  respecting  this  subject,  as  well  as  joints  in  general, 
the  reader  is  referred  to  a  Description  of  the  Bursac  Mucosse  of  the  Human 
Body,  by  Alexander  Monro ;  to  whom  the  world  is  so  much  indebted  for  the 
elucidation  of  many  important  points  in  anatomy  and  physiology. 


238  SUBCUTANEOUS    SYNOVIAL    CAPSULES. 

These    bursae    mucosae    are    very    numerous,  as  will    appear 
from  a  subsequent  account  of  them. 

Several  of  them  are  very  interesting  on  account  of  their  con- 
nexion with  very  important  joints. 

— These  bursae  form  synovial  sheaths  to  the  tendons,  where 
they  run  through  grooves  in  the  bones,  or  urtder  their  vaginal 
ligaments,  or  where  they  glide dover  each  other,  as  in  the  palms 
of  the  hands  and  the  soles  of  the  feet :  but  they  are  especially 
met  with,  wherever  a  tendon  changes  its  direction,  and  converts 
a  bone,  a  cartilage,  or  ligament  into  a  pulley  ;  of  which  instances 
will  be  detailed  hereafter.  When  a  bursae,  or  tendinous  sheath, 
invests  a  tendon  about  to  subdivide,  as  the  flexor  tendons  of 
the  fingers  at  the  wrist,  the  sheath  also  subdivides  so  as  to  send 
a  process  along  each  parting  tendon  ;  a  knowledge  of  which 
fact  is  of  importance  to  the  surgeon,  as  this  membrane  when 
injured,  is  much  disposed  to  continuous  inflammation. 
— The  number  of  these  bursae  vary  in  different  individuals. 
Ollivier  reckons  them  at  one  hundred  pairs. 

Subcutaneous  Synovial  Capsules. 

— These  have  been  long  observed  about  the  wrist,  ankle  and 
knee,  where  they  sometimes  attain  the  size  of  walnuts,  and  are 
known  to  surgeons  when  enlarged  by  disease  under  the  names  of 
ganglions  and  hygroma.  They  were  studied  and  described  for 
the  first  time,  however,  by  Beclard.  They  exist  wherever  the 
skin  is  strongly  and  frequently  moved  over  a  resisting  part :  as 
between  the  skin  and  the  patella  ;  between  the  olecranon  and 
skin  ;  over  the  trochanter  ;  acromion  ;  thyroid  cartilage  ;  at  the 
metacarpal  and  metatarsal  articulations,  &c.  &c.  They  are 
developed  accidentally  in  different  parts,  when  from  any  cause, 
as  in  curvature  of  the  spine,  the  friction  of  the  tendons  is  in- 
creased. When  inflated',  the  cavities  appear  oblong  and  cellula- 
ted,  contain  some  synovial  fluid,  and  look  like  dilated  cells  of 
the  cellular  tissue,  of  which  they  are  in  all  probability  formed  ; 
many  of  them,  however,  are  visible  in  the  foetus  during  the 
latter  period  of  utero-gestation. — r 


PARTICULAR    ARTICULATIONS. 


239 


CHAPTER  V. 


OF  PARTICULAR  ARTICULATIONS. 

The  connexion  of  the  Head  with  the  Vertebra. 

THE  condyles  of  the  occipital  bone,  and  the  corresponding 
cavities  of  the  atlas,  are  covered  with  cartilage.  The  condyle 
and  cavity  on  each  side  are  invested  with  a  synovial  ligament, 
as  described  in  the  general  account  of  articulations. 


Fig.  51.* 


An  anterior  ligament,  (liga- 
mentum  occipito-atloidal  ante- 
nor,)  descends  from  the  front 
part  of  the  great  occipital  fora- 
men, and  is  inserted  into  all  the 
front  part  of  the  atlas,  between 
its  articulating  processes.  That 
portion  of  this  ligament  which 
is  in  the  middle,  and  inserted 
into  the  tubercle  of  the  atlas,  appears  stronger,  and  is  distinct 
from  the  rest  of  it. 

A  posterior  ligament,  (ligamentum  occipito-atloidal  pos- 
terior?) passes  from  the  posterior  margin  of  the  occipital  fora- 
men to  the  upper  edge  of  the  posterior  arch  of  the  atlas. 

From  each  side  of  the  upper  end  of  the  tooth-like  process  of 
the  vertebra  dentata,  a  ligament  (oblique,  or  moderator?) 
passes  upwards  and  outwards,  to  be  inserted  into  the  internal 
side  of  the  basis  of  each  condyle  of  the  occipital  bone.  There 

*  A  posterior  view  of  the  ligaments  connecting  the  atlas,  the  axis,  and  the 
occipital  bone.  The  posterior  part  of  the  occipital  bone  has  been  sawn  away, 
and  the  arches  of  the  atlas  and  axis  removed.  1.  The  superior  part  of  the 
occipito-axoid  ligament,  which  has  been  cut  away  in  order  to  show  the  ligaments 
beneath.  2.  The  transverse  ligaments  of  the  atlas.  3,  4.  The  ascending  and 
descending  slips  of  the  transverse  ligament,  which  have  obtained  for  it  the  title 
of  cruciform  ligament.  5.  One  of  the  odontoid  or  moderator  ligaments.  6.  One 
of  the  occipito-atloid  capsular  ligaments.  7.  One  of  the  atlo-axoid  capsular 
ligaments. 


240  ARTICULATIONS  OF    THE    VERTEBRA. 

is  a  small  ligament,  called  the  middle  straight  ligament  (liga- 
mentum  medium  rectum,)  which  passes  from  the  tip  of  the 
dentated  process,  to  be  inserted  on  the  inner  face  of  the 
occipital  foramen  between  the  insertion  of  the  moderator  liga- 
ments. 

From  the  anterior  margin  of  the  great  occipital  foramen,  a 
ligament  passes  down  on  tfye  inside  of  the  vertebral  cavity, 
over  the  tooth-like  process,  which  is  inserted  in  the  body  of 
the  vertebra  dentata,  and  the  ligaments  connected  with  it. 
This  ligament  is  composed  of  a  number  of  fibrous  bands  called 
by  Caldani,  lacerti  ligamentosi.  This  must  be  dissected  away 
before  the  moderator  and  transverse  ligaments  can  be  brought 
into  view.  See  fig.  52.  It  is  now  more  appropriately  named 
the  occipito-axoid  ligament. 

Fig.    52.*  There     is    also     a     ligament 

which  runs  across  from  one 
side  of  the  atlas  to  the  other, 
to  confine  the  tooth-like  process 
in  its  anterior  cavity,  see  fig. 
51,  page  239,  (transverse  liga- 
ment, ligamentum  transversale 
atlantis.)  This  ligament  ad- 
heres above  to  the  occipital 
bone,  and  below  to  the  body  of 
the  vertebra  dentata.  The  anterior  surface  of  the  tooth-like 
process  plays  on  the  anterior  arch  of  the  atlas ;  the  posterior 
surface  plays  on  this  ligament.  A  synovial  capsule  is  placed 
on  each  surface  of  the  tooth-li£e  process. 

— From  the  middle  of  this  transverse  ligament  a  band  of  fibres 
extend  downward  to  the  vertebra  below,  giving  a  cruciform 
arrangement  to  the  ligament.  See  fig.  52. 

*  The  upper  part  of  the  vertebral  canal,  opened  from  behind  in  order  to  show 
the  occipito-axoid  ligament.  J .  The  basilar  portion  of  the  sphenoid  bone.  2. 
Section  of  the  occipital  bone.  3.  The  atlas,  its  posterior  arch  removed.  4.  The 
axis,  the  posterior  arch  also  removed.  5.  The  occipito-axoid  ligament,  rendered 
prominent  at  its  middle  by  the  projection  of  the  odontoid  process.  6.  Lateral 
and  capsular  ligament  of  the  occipito-atloid  articulation.  7.  Capsular  ligament 
between  the  articulating  processes  of  the  atlas  and  axis. 


ARTICULATIONS  OF    THE    VERTEBRJE.  241 

The  articulating  surfaces  of  the  oblique  process  of  the  atlas 
and  vertebra  dentata  on  each  side,  are  invested  by  a  synovial 
membrane.  There  are,  also,  additional  ligaments  placed 
before  and  behind  these  processes,  that  have  an  effect  on  their 
motions. 

The  uses  of  these  different  ligaments  are  very  obvious  when  they  are  dissected. 
The  transverse  ligament  of  the  atlas,  with  the  synovial  membranes  form  an 
articulation  for  the  tooth-like  process,  which  is  of  a  peculiar  kind.  The  liga- 
ments that  pass  from  this  process,  to  the  bones  of  the  condyles  of  the  occipital 
bone,  must  have  an  effect  in  restraining  the  rotation  of  the  head  and  atlas  on 
this  process,  and  therefore  have  been  called  moderator  ligaments. 

The  Articulations  of  the   Vertebrae  with  each  other. 

To  acquire  a  perfect  idea  of  the  construction  of  the  Spine  it  is  necessary  to 
examine,  at  least,  two  preparations  of  it :  in  one  of  which  the  bodies  of  the 
vertebrse  should  be  sawed  off  from  the  processes,  so  that  the  spinal  canal  may 
be  laid  open. 

The  bodies  of  all  the  vertebrae,  except  the  atlas,  are  connected 
to  each  other  by  the  intervertebrdl  fibre-cartilaginous  matter 
described  in  page  138,  which  unites  them  very  firmly,  at  the 
same  time  that  it  allows  of  some  motion,  in  consequence  of  its 
elasticity  and  compressibility.  This  connexion  is  strengthened 
by  two  ligaments,  which  extend  the  whole  length  of  the  spine, 
from  the  second  cervical  vertebra  to  the  sacrum. 

The  first  of  these,  denominated  the  anterior  vertebral 
ligaments ,  covers  a  considerable  part  of  the  anterior  sur- 
face of  the  bodies  of  the  vertebrae  ;  it  is  thickest  in  the  middle, 
and  varies  in  its  breadth  in  different  parts  of  the  verte- 
bral column  ;  it  adheres  very  firmly  to  the  intervertebral 
substance,  and  not  so  firmly  to  the  bodies  of  the  vertebrae. 
It  has  the  shining  silver-like  appearance  of  tendon,  and  seems 
to  consist  entirely  of  longitudinal  fibres.  There  are  many 
fibres  which  appear  to  be  connected  with  it,  that  do  not  extend 
the  whole  length  of  the  spine. 

On  the  posterior  surface  of  the  bodies  of  the  vertebrae,  in  the 
cavity  which  contains  the  spinal  marrow,  is  the  posterior  or 
internal  vertebral  ligament,  which,  like  the  anterior,  extends 
from  the  upper  part  of  the  spine  to  the  sacrum. 

In  its  progress  downwards  it  is  broader  where  it  is  in  contact 
21 


242  ARTICULATIONS  OF    THE    VERTEBRJE. 

with  the  intervertebral  matter,  and  narrower  about  the  middle 
of  each  of  the  bodies  of  the  vertebrae.  It  appears  to  consist  of 
longitudinal  tendinous  fibres,  which  are  similar  to  those  of  the 
anterior  ligament.  The  fibres  of  which  these  ligaments  are 
composed,  are  more  closely  connected  by  origin  and  insertion 
with  the  intervertebral  matter,  than  with  the  bodies  of  the 
vertebrae.  Some  of  the  fibres  are  inserted  into  the  next  verte- 
brae or  intervertebral  substance  below  their  place  of  origin, 
others  into  the  second  or  third,  and  some  into  the  fourth  or 
fifth. 

The  oblique  processes  of  the  vertebrae  are  covered  with 
cartilage,  and  are  invested  with  a  synovial  membrane,  like  the 
other  movable  articulations.  In  the  neck  and  back  these 
membranes  are  thin  and  delicate  ;  but  in  the  loins  they  are 
blended  with  ligamentous  fibres  which  give  them  additional 
strength. 

Some  of  the  most  curious  and  interesting  ligaments  of  the 
spine,  or  indeed  of  the  body,  are  those  which  are  attached  to 
the  bony  plates  or  arches  that  extend  from  the  oblique  to  the 
spinous  processes  of  each  vertebrae.  These  plates  form  a  great 
portion  of  the  posterior  part  of  the  vertebral  canal  and  the 
vacant  spaces  between  them  are  filled  up  by  these  ligaments, 
which  extend  from  the  plates  of  each  upper  vertebra  of  those 
of  the  next  vertebra  below. 

They  are  situated  between  the  spinal  process  and  the  oblique 
processes  on  each  side. 

They  are,  therefore,  two  distinct  ligaments  between  the  two 
vertebrae,  one  on  each  side  of  the  spinal  process  ;  and  as.  they 
extend  only  from  the  plates  or  arches  of  one  vertebra  to  those 
of  the  other,  they  must  necessarily  be  very  short.  They  are 
much  more  conspicuous  on  the  internal  surface  of  the  vertebral 
cavity  than  they  are  externally.  They  are  thick  and  substantial, 
and  very  elastic ;  their  color  resembles  that  of  a  yellowish 
adeps  ;  and  from  that  circumstance  they  are  called  the  yellow 
or  elastic  ligaments.  They  complete  the  cavity  for  the  spinal 
marrow.  There  are  twenty-three  pairs  in  all. 

As  the  plates  or  arches  to  which  they  are  connected  must 


ARTICULATIONS  OF    THE    VERTEBRJE.  243 

recede  from    each  other,  when  the  spine  is    bent  forwards,  it 

seems  that  they  should  be  elastic. 

Fig.  53.*  There  are  also  ligaments   between 

the  spinous  processes,  which  extend 
from  the  under  surface  of  one  spinous 
process  to  the  upper  surface  of  the 
spinous  process  below  it.  These  are 
composed  of  tendinous  shining  fibres, 
and  are  sufficiently  loose  to  permit 
the  anterior  flexure  of  the  vertebral 
column.  From  their  situation  they 
are  denominated  interspinal  liga- 
ments. 

There  is  also  a  thin  and  narrow  ligamentous  band,  which 
extends  from  the  spinous  process  of  the  seventh  cervical  verte- 
bra to  the  spinous  processes  of  the  os  sacrum,  and  adheres  to 
the  ends  of  the  intermediate  spinous  processes.  It  is  exterior 
to  the  tendinous  origins  of  the  trapezii  and  latissimi  dorsi 
muscles.  The  upper  portion  is  slightly  connected  to  the 
trapezius,  the  lower  part  adheres  more  firmly  to  the  latissimus 
dorsi. 

The  ligamentum  nucha,  ligament  of  Diemerbrcek,  as  it  has 
been  denominated,  is  a  narrow  but  firm  strip,  which  extends 
from  the  spinous  process  of  the  last  cervical  vertebra,  to  the 
occipital  bone,  at  or  near  its  protuberance.  It  is  very  strongly 
developed  in  all  the  larger  quadrupeds,  with  pendant  heads. 
That  portion  of  the  trapezius  muscle  which  is  between  the 
occipital  bone  and  the  seventh  cervical  vertebra,  originates 
from  it,  or  is  intimately  connected  with  it ;  and  a  portion  of  the 
splenius  muscle  is  also  connected  with  it. 

From  the  internal  surface  of  this  ligament,  a  thin  tendinous 
membrane  arises,  whose  fibres  run  obliquely  upwards  and 

*  A  posterior  view  of  a  part  of  the  thoracic  portion  of  the  vertebral  column, 
showing  the  ligaments  connecting  the  vertebrae  with  each  other  and  the  ribs 
with  the  vertebrae.  1.  The  supra-spinous  ligament.  2,  2.  The  ligamenta  sub- 
flava,  or  yellow  elastic  ligaments,  connecting  the  laminae.  3.  The  anterior  costo- 
transverse  ligament.  4.  The  posterior  costo-transverse  ligaments. 


V 

244  ARTICULATION   OF    THE  LOWER    JAW. 

forwards,  and'  are  inserted  into  the  spinous  processes  of  each 
of  the  cervical  vertebrae  above  the  seventh,  and  also  into  the 
atlas  and  the  os  occipitis.  Attached  to  the  ligamentum  nuchse 
and  to  the  spine,  this  membrane  seems  like  a  partition  between 
the  muscles  which  lie  on  each  side  of  the  back  of  the  neck. 


After  inspecting  the  different  ligaments  of  the  spine,  it  will  be  obvious-  that  the 
yellow  ligaments  are  among  the  most  important  of  them  ;  in  consequence  of 
their  position,  their  strength)  and  their  elasticity. 

Articulation  of  the  Lower  Jaw,  (Temporo  maxillary.} 

The  glenoid  cavity  of  the  tempora4  bone  with  the  tubercle 
before  it,  and  the  condyle  of  the  lower  jaw,  are  covered  with 
cartilages.  A  cartilage  is  placed  between  them  called  inter- 
articular)  which  being  flexible,  is  accommodated  to  the  con- 
vexity of  the  condyle  and  hollowness  of  the  glenoid  cavity, 
and  also  to  the  figure  of  the  aforesaid  tubercle  to  which  it  is 
extended.  A  synovial  capsule,  or  bag,  invests  the  glenoid 
cavity  and  the  tubercle,  and  covers  the  upper  surface  of  the 
cartilage.  A  second  capsule  of  the  same  kind  is  attached  to 
the  condyle  of  the  lower  jaw,  and  the  lower  surface  of  the  car- 
tilage. A  few  ligamentous  fibres  extend  from  the  circumfer- 
ence of  the  cavity  and  tubercle  of  the  temporal  bone,  over  both 
synovial  capsules  and  the  cartilage  between  them,  to  the  lower 
jaw  below  the  condyle,  and  appear  to  be  attached  to  the 
cartilage. 

These  fibres  are  collected  in  such  numbers,  on  the  external 
and  internal  sides  of  the  articulation,  that  they  have  been  called 
the  external  and  internal  lateral  ligaments. 

Another  ligament  called  stylo-maxillary,  is  mentioned  which 
arises  from  the  styloid  process  of  the  temporal  bone,  and  is  in- 
serted into  the  lower  jaw  near  its  angle  ;  but  this  seems  rattier 
appropriated  to  the  stylo-glossus  muscle  than  to  this  articulation. 

In  consequence  of  this  structure,  the  condyle  of  the  lower 
jaw  moves  out  of  the  glenoid  cavity  upon  the  tubercle,  when 
the  mouth  is  opened  widely. 


ARTICULATIONS  OF    THE    SHOULDER,  245 

Articulation  of  the  Clavicle  and  Sternum,  called  Sterno-clavicular. 

The  connexion  of  the  clavicle  and  sternum  resembles  strongly 
that  of  the  lower  jaw  and  temporal  bone.  A  movable  cartilage 
is  placed  between  the  articulating  surfaces,  with  a  distinct  syno- 
vial  capsule  on  each  side  of  it,  applied  in  the  usual  manner  to 
the  corresponding  surface  of  the  clavicle  and  of  the  sternum. 
Exterior  to  these  capsules  and  the  intervening  cartilage,  are 
many  ligamentous  fibres,  which  are  most  numerous  on  the  ante- 
rior and  posterior  surfaces,  but  diverge  from  each  other  as  they 
proceed  from  the  clavicle  to  the  sternum,  and  are,  therefore, 
called  Radiated  Ligaments. 

There  is  a  strong  ligament  called  the  Inter  clavicular,  which 
passes  across  the  sternum  internally,  from  one  clavicle  to  the 
other. 

And  another  ligament,  which  arises  from  the  inferior  rough 
surface  of  the  clavicle,  near  the  sternum,  which  is  inserted  into 
the  cartilage  of  the  first  rib. 

This  is  called  the  Rhomboid,  or  Costo-clavicular  ligament. 

Articulations  of  the  Clavicle  and  Scapula,  (Scapulo-clamcular.) 

Fig.  54.*  These  are  two  in  number ; 

one  which  connects  the  acro- 
mion  and  external  end  of  the 
clavicle  called  acromio-clavicu- 
lar,  and  one  which  connects 
the  lower  surface  of  the  outer 
part  of  the  clavicle  with  the 
coracoid  process  of  the  scapula, 
called  coraco-Clavicular. 
Acromio-clavicular.  The  small  surfaces  of  the  clavicle  and 
scapula,  which  are  in  contact  with  each  other,  are  furnished 

*  The  ligaments  of  the  sterno-clavicular  and  costo- sternal  articulations.  1. 
The  anterior  sterno-clavicular  ligament.  2.  The  inter-clavicular  ligament.  3. 
The  costo-clavicular  or  rhomboid  ligament,  seen  on  both  sides.  4.  The  inter- 
articular  fibro-cartilage,  brought  into  view  by  the  removal  of  the  anterior  and 
posterior  ligaments.  5.  The  anterior  costo-sternal  ligaments  of  the  first  and 
second  ribs. 

21* 


246  ARTICULATIONS  OF    THE    SHOULDER. 

with  the  apparatus  of  a  movable  articulation.  They  are 
covered  with  cartilage,  and  are  invested  with  a  small  synovial 
capsule.  The  upper  and  lower  surfaces  of  the  extremities  of 
the  clavicle  and  acromion  are  covered  by  a  ligamentous  mem- 
brane, which  is  called,  from  its  situation,  the  superior  and  infe- 
rior ligament  of  this  articulation. 

Coraco-clavicular,  consisting  of  two  portions,  conoid  and  trape- 
zoid. But  these  bones  are  more  firmly  connected  by  the  liga- 
ment which  passes  to  the  coracoid  process  of  the  scapula  from 
the  under  side  of  the  clavicle,  and  is  very  strong.  ISome  of  tne 
fibres  which  compose  this  ligament  are  so  arranged  that  they 
have  the  appearance  of  an  inverted  cone :  the  remaining  fibres 
appear  like  another  ligament,  and  therefore  they  have  been 
called  the  trapezoid  and  conoid  ligaments. 

— The  base  of  the  conoid  ligament  is  upwards,  and  its  apex 
or  origin  is  at  the  root  of  the  coracoid  process.  It  is  the  stronger 
of  the  two.  The  trapezoid  is  at  the  outer  side  of  the  conoid. 
It  is  broad  and  thin,  with  its  fibres  separated  by  interstices.  It 
rises  from  the  root  of  the  coracoid  process, 'and  is  inserted  on  an 
oblique  ridge,  leading  from  the  tubercle  of  the  clavicle  to  its 
acromial  end. — 

By  their  situation  and  strength  they  are  enabled  to  retain  the 
bones  in  their  proper  relative  positions,  at  the  same  time  that 
they  permit  a  peculiar  rotary  motion. 

— There  is  a  bifid  ligament  called  Kgamentum  bicorne,  arising 
from  the  root  of  the  coracoid  process,  at  the  inner  side  of  the 
conoid,  which  runs  inwards  in  front  of  the  subclavius  muscle, 
to  which  it  serves  as  a  fascia,  and  bifurcates ;  one  horn  is 
attached  to  the  under  surface  of  the  clavicle  near  the  rhomboid 
ligament,  and  the  other  to  the  end  of  the  first  rib,  under  the 
tendon  of  the  subclavius  muscle. — 

^Articulation  of  the  Os  Humeri  and  Scapula,  (Scapulo-humeral.) 

The  spherical  portion  of  the  upper  extremity  of  the  os  humeri 
is  the  part  of  that  bone  which  is  principally  concerned  in  the 
articulation,  and  is  covered  with  cartilage  ;  as  is  also  the  glenoid 
-cavity  of  the  scapula. 


ARTICULATIONS   OF    THE    SHOULDER. 


247 


Fig.  55.*  The  glenoid  cavity  of  the  scapula, 

which  is  so  small  in  the  dried  bone", 
when  compared  with  the  head  of 
the  os  humeri,  is  enlarged  lay  the 
long  tendon  of  the  biceps  muscle, 
which  is  attached  to  the  upper  edge 
of  its  margin,  and  then  divides  and 
passes  down  on  each  side  of  the 
cavity,  increasing  the  breadth  of  it 
considerably,  thus  forming  what  is 
called  iheglenoid  ligament,  deepen- 
ing the  socket,  and  giving  greater 
latitude  of  motion  to  the  arm,  from  its 
elasticity,  than  if  the  socket  had  all 
been  formed  of  bone.  It  appears  to  be  blended  with  the  carti- 
lage that  lines  the  cavity,  and  also  with  the  capsular  ligament 
which  is  exterior  to  it. 

The  .articulating  surface,  thus  composed,  is  perfectly  regular 
and  uniform. 

The  synovial ,  ligament,  in  this  articulation,  is  so  blended 
with  an  external  stronger  ligament,  that  it  cannot  be  separated 
in  the  recent  subject ;  but,  notwithstanding,  it  is  applied  to  the 
articulating  surfaces  in  the  same  way  that  it  is  applied  to  the 
other  joints  forming  a  capsule.  The  stronger  exterior  lamina 
is,  of  course,  only  applied  to  that  part  of  the  synovial  capsule 
which  proceeds  from  the  margin  of  one  cartilaginous  articulating 
surface  to  the  other :  it  appears  to  be  most  intimately  connected 
with  the  periosteum,  and  is  rendered  more  firm  and  thick  in 
particular  parts,  by  the  addition  of  fibres  from  the  tendons  of  the 
supra  and  infra-spinatus,  and  subscapularis  'muscles  with  which 
it  is  blended. 

It  arises  from  the  scapula  at  a  small  distance  from  the  mar- 


*  The  ligaments  of  the  scapula  and  shoulder  joint.  1.  The  superior  acromio- 
clavicular  ligament.  2.  The  coraco-clavicular  ligament ;  this  aspect  of  the 
ligament  is  named  trapezoid.  3.  The  coraco-acromial  ligament.  4.  Coracoid 
or  transverse  ligament  as  it  is  sometimes  called.  5.  Capsular  ligament.  6. 
Coraco-humeral  ligament.  7.  The  long  tendons  of  the  biceps  issuing  from  the 
capsular  ligament,  and  entering  the  bicipital  groove. 


248  ARTICULATION  OF  THE  ELBOW. 

gin  or  edge  of  the  glenoid  cavity,  as  formed  by  the  tendon  of 
the  biceps,  and  is  inserted  into  the  os  humeri  at  a  small  distance 
from  the  edge  of  the  cartilaginous  articulating  surface  ;  and,  if 
dissected  away  from  the  bones,  would  appear  like  a  cylindrical 
bag  with  both  extremities  open. — The  capsular  ligament  is 
thickened  in  front  by  a  band  of  fibres,  arising  from  the  outer  part 
of  the  back  surface  of  the  coracoid  process,  which  proceeds 
beneath  the  triangular  ligament  to  the  upper  part  of  the  os 
humeri ;  it  is  closely  blended  with,  and  forms  a  part  of  the  cap- 
sular ligament,  and  is  denominated  tbe  coraco-humeral  ligament, 
or  ligamentum  adscititium. — 

The  long  tendon  of  the  biceps  muscle,  in  the  groove  at  the 
head  of  the  os  humeri,  appears  to  penetrate  this  ligament ;  but 
it  is  not  within  the  cavity  of  the  synovial  membrane ;  for  this 
membrane  sends  down  a  process  like  the  finger  of  a  glove, 
which  lines  the  groove,  and  is  reflected  from  its  surface  upon 
the  surface  of  the  tendon,  and  covers  it  during  its  whole  extent, 
being  reflected  from  the  tendon,  at  its  upper  termination,  to  the 
adjoining  surface  ;  so  that  the  tendon  is  in  fact  outside  of  the 
synovial  capsule,  which,  therefore,  confines  the  synovia  com- 
pletely. 

This  capsular  ligament,  which  is  one  of  the  strongest,  would 
not  avail  much  in  keeping  the  bones  in  their  proper  situations, 
if  the  muscles  and  their  tendons  were  not  disposed  in  such  a 
manner,  that  when  the  muscles  act,  their  power  is  excited  to 
the  same  effect.  In  some  cases  of  paralytic  affection,  where 
the  muscles  exert  no  influence,  the  weight  of  the  arm,  when  it 
is  allowed  to  hang  without  support,  draws  the  head  of  the  os 
humeri,  below  the  glenoid  cavity,  notwithstanding  the  capsu- 
lar ligament.  At  tfce  same  time  it  ought  to  be  observed,  that 
this  ligament  must  be  lacerated  in  every  case  of  complete 
luxation  of  the  os  humeri ;  as  it  cannot  possibly  distend  suffi- 
ciently to  permit  the  separation  of  the  bones  to  the  extent  which 
then  takes  place. 

The  Articulation  of  the  Elbow. 

Those  surfaces  of  the  os  humeri,  ulna,  and  radius,  which  move 
upon  each  other,  are  covered  with  cartilage. 


ARTICULATION    OF    THE    WRIST. 


249 


Fig.  56.*  The  motion   of  the  ulna  and   radius  on   the 

os  humeri  is  that  of  the  simple  flexion  and 
extension.  The  cylindrical  head  of  the  Radius 
performs  a  part  of  a  revolution,  nearly  on  its 
own  axis,  without  moving  from  the  depression 
in  the  side  of  the  ulna,  with  which  it  is  in 
contact. 

The  synovial  membrane  adheres  very  firmly 
to  the  surface  covered  with  cartilage  on  each 
of  the  bones,  and  is  reflected  from  the  margin 
of  this  surface,  on  one  bone,  to  that  of  the 
others.  As  the  principal  motion  performed  is 
hinge-like,  the  principal  ligaments  are  on  the 
sides.  There  is  also  a  circular  ligament,  which 
arises  from  the  ulna  and  invests  the  narrow  part 
of  the  radius  immediately  below  its  cylindrical 
head  like  a  loop,  to  confine  the  radius  in 
contact  with  the  ulna,  and  at  the  same  time 
permit  its  motion. 

This  ligament  is  so  blended  with  the  synovial  membrane,  that 
it  sometimes  cannot  be  separated  from  it. 

The  lateral  ligaments  are  denominated  from  their  origin  and 
insertion,  Brachio-radial,  and  Brachio-cubital,  or  External  and 
Internal.  The  external  is  a  strong,  narrow  band,  attached 
above  to  the  external  condyle  of  the  humerus,  and  below 
to  the  orbicular  ligament,  and  adjoining  ridge  of  the  ulna. 
The  internal,  is  thick  and  triangular  ;  its  apex  is  attached  to 
the  internal  condyle  of  the  humerus,  and  its  lower  or  broad 
part  is  inserted  into  the  margin  of  the  greater  sigmoid  fossa  of 
the  ulna  extending  from  the  coronoid  process  to  the  olecra- 
non. — Posterior  to  it  runs  the  ulnar  nerve.  The  ligament 
which  invests  the  neck  of  the  radius  is  called  Coronary  or 
Orbicular. 


*  An  internal  view  of  the  ligaments  of  the  elbow  joint.  1.  The  anterior 
ligament.  2.  The  internal  lateral  ligament.  3.  The  orbicular  ligament.  4.  The 
oblique  ligament.  5.  The  interosseous  ligament.  6.  The  internal  condyle  of 
ihe  humerus,  which  conceals  the  posterior  ligament. 


250 


ARTICULATION    OF    THE    WRIST. 


— The  orbicular  ligament  is  a  firm  band 
Fig.  57.*  several  lines  in  breadth,  which  surrounds 
the  head  of  the  radius,  and  is  attached  by 
each  end  to  the  extremities  of  the  lesser  sig- 
moid  cavity.  It  is  strongest  behind  where  it 
receives  the  external  lateral  ligament. — On  its 
inner  surface  it  is  lined  by  a  process  of  syno- 
vial  membrane  from  the  elbow  joint. — When 
this  ligament  is  ruptured,  as  often  occurs  in 
children,  the  head  of  the  radius  readily  slips 
from  its  place. — 

There  are  also  some  ligamentous  bands, 
which  run  upon  the  front  and  back  parts  of 
the  joint  to  strengthen  it,  which  are  called 
Anterior  and  Posterior  accessory  ligaments. — 
They  are  broad  thin  membranous  layers 
placed  on  the  outer  surface  of  the  synovial 
membrane,  and  are  both  attached  to  the  hume- 
rus  above,  and  upon  the  sides  to  the  lateral 
ligaments :  below  the  posterior  is  attached  to 
the  olecranon  ;  the  anterior  to  the  coronoid  process  of  the 
ulna  and  to  the  lateral  ligament.  Within  the  synovial  mem- 
brane, in  the  upper  margins  of  the  depressions  for  the  olecranon 
and  coronoid  processes  of  the  ulna,  are  the  adipose  substances 
usually  found  in  joints. 

Articulation  of  the  Wrist. 

The  structure  of  the  wrist  is  particularly  complex,  because  it  consists  of  three 
articulations,  which  are  contiguous  to  each  other,  viz.  That  of  the  ulna  and 
radius;  of  the  radius  and  first  row  of  carpal  bones,  radio-carpal;  and  of  the 
first  and  second  row  of  carpal  bones  with  each  other,  middle  carpal  joint. 

An  oblong  convex  head  is  formed  by  the  upper  surfaces  of 
the  scaphoides   and  lunare,  and  a  portion  of  the  upper  surface 

*  External  view  of  the  elbow  joint.  1.  Humerus.  2.  Ulna.  3.  Radius.  4. 
The  external  lateral  ligament  inserted  below  into  the  orbicular  ligament.  6. 
The  posterior  extremity  of  the  orbicular  or  coronary  ligament,  spreading  out  at 
its  insertion  into  the  ulna.  7.  The  anterior  ligament,  scarcely  seen  in  this  view 
of  the  articulation.  8.  The  posterior  ligament,  thrown  into  folds  by  the  exten- 
sion of  the  joint. 


ARTICULATION    OF    THE    WRIST. 


251 


of  the  cuneiforme  bone.  This  head  is  covered  by  one  cartilage, 
which  is  so  uniform  that  the  different  bones  cannot  be  distin- 
guished from  each  other.  The  lower  end  of  the  radius  i^  arti- 
culated with  this  head,  but  does  not  cover  the  whole  of  it ;  a 
portion  of  this  head,  therefore,  is  under  the  ulna,  but  not  in 
contact  with  that  bone  :  for  the  cartilage  which  lines  the  con- 
cavity of  the  radius,  is  continued  beyond  the  radius,  so  as  to 
cover  the  remainder  of  the  head,  formed  by  the  carpal  bones. 

Fig.  58.*  — This  cartilage  which  is  extended 

from  that  covering  the  radius,  is 
attached  to  a  depression  on  the 
inner  surface  of  the  styloid  pro- 
cess of  the  ulna.  It  is  called  the 
inter-articular  or  from  its  shape  the 
triangular  fibro-cartilage.  The  sy- 
novial  membrane  forming  the  joint 
between  this  cartilage  and  the  end 
of  the  ulna  is  loose  and  is  called  the 
sacciform  membrane,  (see  fig.  58.) 
The  lower  end  of  the  ulna  is  in 
contact  with  the  upper  surface  of 
this  cartilage,  and  is  articulated  lat- 
erally with  the  semilunar  cavity  of 
the  radius.  This  semilunar  cavity 

*  A  careful  dissection  being  made,  the  ligaments  of  the  carpus  will  appear 
as  seen  in  this  and  the  following  figures. — 

Dorsal  surface,  a.  External  lateral  ligament.  It  runs  from  the  styloid  process 
of  radius  to  os  scaphoides.  b.  Internal  lateral  ligament  which  runs  from  the 
styloid  process  of  the  ulna  and  divides  into  two  fasciculi,  one  of  which  is  attached 
to  the  pisiform,  the  other  to  the  cuneiforme  bone.  d.  Posterior  or  dorsal  ligament 
of  the  radio-carpal  articulation.  They  are  thin  and  weak  and  run  from  the 
radius  to  the  first  row  of  bones,  g.  Posterior  radio  ulnar  ligament.  ».  A  pos- 
terior or  dorsal  thin  band  of  fibres,  which  connects  the  two  rows  of  bones 
together.  L  "Dorsal  ligaments,  which  connect  the  metacarpal  bones  together  at 
their  base.  n.  Dorsal  ligament  connecting  the  anterior  ends  of  these  bones. 
o.  A  middle  dorsal  ligament  stretched  from  the  second  metacarpal  bone  to  the 
trapezoid.  p.  An  external  ligament  running  from  this  bone  to  the  trapezium; 
another  internal  one  running  from  this  bone  to  the  os  magnum,  is  not  here  seen. 
r.  An  oblique  ligament,  running  from  the  os  unciforme  to  the  third  metacarpal 
bone.  s.  Capsular  ligament  of  the  metacarpo-carpal  articulation  of  the  thumb. 
t.  A  sort  of  capsular  ligament  of  the  metacarpo-carpal  joint  of  the  little  finger. 
n.  The  place  of  dorsal  ligament  supplied  in  a  great  measure  by  extensor  tendon. 
z.  Lateral  ligament. 


252 


ARTICULATION    OF    THE    WRIST. 


is  lined  by  a  cartilaginous  process,  continued  from  the  upper 
surface  of  the  aforesaid  cartilage ;  so  that  the  extremity  and 
the  side  of  the  ulna  play  upon  the  cartilage  continued  from  the 
radius.  This  articulation  of  the  ulna  and  radius  is  distinct  from 
that  of  the  radius  and  carpus. 

Fig.  59.*  A  synovial  membrane  covers  the 

•articulating  head  formed  by  the 
three  bones  of  the  carpus,  and  is 
reflected  from  the  margin  of  their 
cartilaginous  surface,  to  the  carti- 
lage at  the  end  of  the  radius.  A 
plait  or  fold  of  this  membrane 
passes  from  the  head  of  the  carpus, 
at  tile  junction  of  the  scaphoides 
and  lunare,  to  the  opposite  part  of 
the  cartilage  of  the  radius,  and  has 
been  called  the  Mucous  Ligament, 
(ligamentum  mucosum.) 

A  strong  ligament  (internal  lat- 
eral) is  placed  on  the  internal  side . 
of  this  articulation,  which  arises 
from  the  styloid  process  of  the  ulna,  and  is  inserted  into  the 
anterior  transverse  ligament  which  confines  the  flexor  tendons, 
and  into  the  pisiforme  and  cuneiforme  bones. 


*  Anterior  or  palmar  surface,  a.  External  lateral  ligament,  b.  Internal 
lateral  ligament,  c.  Three  anterior  or  palmar  ligaments  belonging  to  the  articu- 
lation of  the  first  row  of  bones  with  the  radius,  or  the  radio-carpal  articulation. 
They  run  from  the  radius  to  the  bones  of  the  carpus,  e.  Two  very  strong 
inferior  ligaments  which  connect  the  pisiform  and  cuneiform  bones  together : 
besides  these,  four  other  ligaments  are  discovered  at  this  articulation;  an  exter- 
nal, an  internal,  and  two  lateral.  So  strong  is  this  articulation,  that  the  pisiform 
bone  is  rarely  if  ever  dislocated.  /.  Anterior  radio-lunar  ligament.  Articula- 
tion of  the  two  bones  together.  I.  An  anterior  or  palmar  ligament,  running 
from  the  os  magnum,  and  diverging  to  the  three  inner  bones  of  the  first  row. 
m.  Palmar  ligaments  which  connect  the  metacarpal  bones  at  their  base.  There 
is  another  set  of  fibres  called  the  interosseous,  not  seen  here,  which  connect 
these  bones  at  their  base.  n.  Palmar  or  transverse  ligament  at  the  anterior  end 
of  these  bones,  s.  Capsular  ligament  of  the  thumb,  u.  Ligamento-cartilagi- 
nous,  thickens  over  the  first  joint  of  the  fingers,  v.  Lateral  ligaments,  y.  Pal- 
mar or  glenoid  ligaments,  as  they  seem  to  deepen  the  articular  surface  for  the 
phalanges. 


ARTICULATION    OF    THE    WRIST. 


253 


Fig.  60.* 


Another  ligament,  (external  lateral,)  on  the  external  side, 
arises  from  the  styloid  process  of  the  radius,  and  is  inserted  into 
the  scaphoides,  some  of  its  fibres  being  continued  int6  the 
aforesaid  transverse  ligament,  and  the  trapezium. 

There  are  two  broad  irregular  ligamentous  membranes :  one 
of  which  arises  from  the  anterior  margin  of  the  articulating 
surface  of  the  radius ;  and  the  other  from  the  posterior  margin. 
One  of  them  is  inserted  anteriorly,  and  the  other  posteriorly, 
into  the  margin  of  the  corresponding  surface  of  the  scaphoides, 
lunare  and  cuneiforme.  They  adhere  to  the  synovial  membrane  ; 
but  in  some  places  this  membrane  appears  through  apertures 
which  are  in  them. 

The  surfaces,  by  which  the 
first  and  second  rows  of  carpal 
bones  are  articulated  with  each 
other,  are  very  irregular.  The 
magnum  and  part  of  the  unci- 
forme  form  a  prominent  oblong 
head  ;  on  each  side  of  which  is 
a  much  lower  surface,  formed 
by  the  trapezium  and  trapezoides 
externally,  and  the  remaining  por- 
tion of  the  unciforme  internally ,f 
The  scaphoides,  lunare,  and 
cuneiforme,  form  a  cavity  which 
corresponds  with  this  head,  and 
also  with  the  lower  surface 

*  A  diagram  showing  the  disposition  of  the  five  synovial  membranes  of  the 
wrist  joint.  1.  The  sacciform  membrane.  2.  The  second  synovial  membrane. 
3,  3.  The  third,  or  large  synovial  membrane.  4.  The  synovial  membrane  be- 
tween, the  pisiform  bone  and  the  cuneiforme.  5.  The  synovial  membrane  of 
the  metacarpal  articulation  of  the  thumb.  6.  The  lower  extremity. of  the  radius. 
7.  The  lower  extremity  of  the  ulna.  8.  The  interarticular  fibro-cartilage.  S. 
The  scaphoid  bone.  L.  The  semilunare.  C.  The  cuneiforme  ;  the  interosseous 
ligaments  are  seen  passing  between  those  three  bones  and  separating  the  articu- 
lation of  the  wrist  (2)  from  the  articulation  of  the  carpal  bones  (3).  P.  The 
pisiforme.  T.  The  trapezium.  2T.  The  trapezoides.  M.  The  os  magnum. 
U.  The  unciforme;  interosseous  ligaments  are  seen  connecting  the  os  magnum 
with  the  trapezoides  and  unciforme.  9.  The  base  of  the  metacarpal  bone  of  the 
thumb.  10,  10.  The  bases  of  the  other  metacarpal  bones. 

f  The  palm  of  the  hand  is  supposed  to  present  forward. 
22 


254         ARTICULATION  OF  THE  CARPAL  BONES. 

formed  by  the  unciforme ;  while  another  surface  of  the  sea- 
phoides  is  articulated  with  the  trapezium  and  trapezoides. 
These  corresponding  surfaces,  formed  by  the  two  rows  of  carpal 
bones,  irregular  as  they  are,  compose  but  one  articulation, 
which  is  capable  of  a  limited  flexion  and  extension.  It  has  a 
synovial  membrane,  with  two  lateral  ligaments,  and  an 
anterior  and  posterior  ligament ;  these  last,  however,  are  short, 
and  can  be  best  examined  from  within,  by  cutting  open  the 
articulation. 

The  bones  of  each  row  move  laterally  upon  each  other. 
Their  lateral  surfaces,  which  are  in  contact,  are  covered  with 
cartilage ;  and  the  synovial  sac  which  exists  between  the  first 
and  second  row  of  bones,  sends  off  processes  between  these 
surfaces,  which  are  disposed  like  the  ordinary  synovial  mem- 
branes in  other  articulations ;  adhering,  as  is  supposed,  to  each 
of  the  cartilaginous  surfaces,  while  they  communicate  with  the 
larger  cavity  between  the  two  rows. 

— Interosseous  ligaments  pass  between  the  three  outer  bones 
of  the  upper  row,  and  the  three  inner  of  the  lower  so  as  to 
intercept  at  these  points  the  distribution  of  the  synovial  mem- 
branes between  the  individual  bones  of  each  row.  By  this 
means  there  is,  as  seen  in  fig.  60,  including  the  sacciform  mem- 
brane, five  synovial  membranes  in  the  wrist  joint. 

Articulation  of  the  Carpal  and  Metacarpal  Bones. 

The  metacarpal  bones  are  connected  to  the  last  row  of  the 
carpus  by  surfaces  which  are  covered  with  cartilages,  and 
supplied  with  synovial  membranes,  as  the  most  movable 
articulations  are  ;  but  the  ligaments  which  connect  these  bones 
do  not  permit  much  motion  between  them.  The  ligaments 
are  all  dorsal  and  palmar.  The  irregularity  of  the  articulating 
surfaces  of  the  metacarpal  bones  of  the  index  and  middle  finger 
also  contribute  to  restrain  their  motion  ;  and  these  bones  accord- 
ingly move  less  than  the  other  two  metacarpal  bones,  whose 
surfaces  are  better  adapted  for  motion. 


ARTICULATION  OF    THE  RIBS.  255 

Articulation  of  the  Fingers. 

The  first  joint  of  the  fingers  has  a  large  synovial  membrane, 
which  invests  the  head  of  the  metacarpal  bone  and  the  corres- 
ponding cavities  of  the  bones  of  the  first  phalanx.  On  each 
side  is  a  strong  lateral  ligament,  which  arise  from  the  side  of  the 
head  of  the  metacarpal  bone,  and  is  inserted  into  the  side  of  the 
base  of  the  first  phalanx. 

Anteriorly  there  is  also  a  ligament,  which,  although  thick 
and  strong,  is  very  flexible.  It  is  thickened  by  cartilaginous 
matter  on  its  palmar  face,  which  serves  as  a  sort  of  pulley  to  the 
tendons,  and  increases  their  power  by  removing  them  from  their 
line  of  action.  Posteriorly  the  expansion  of  the  tendons  of  the 
extensor  muscle,  and  the  tendons  of  the  interossei,  have  the 
effect  of  a  ligament. 

The  different  phalanges  are  articulated  with  each  other  in  a 
similar  manner.  The  lateral  ligaments  are  very  strong :  the 
tendon  of  the  extensor  covers  the  articulation  posteriorly  ;  and 
anteriorly,  under  the  flexor  tendons,  there  is  a  soft,  but  thick 
ligamentous  substance.  The  metacarpal  bone  of  the  thumb 
differs  greatly  from  the  other  metacarpal  bones  in  its  articulation 
with  the  wrist,  as  respects  its  motions.  The  articulating  surfaces 
are  calculated  for  lateral  motion  as  well  as  flexion  and  exten- 
sion ;  and  there  are  no  ligaments  which  prevent  it.  Its  capsular 
ligament  forms  a  complete  sac.  The  first  joint  of  the  thumb 
resembles  considerably  that  of  the  fingers  ;  and  the  second  joint 
resembles  the  last  of  the  phalanges. 

Articulation  of  the  Ribs. 

The  ribs  are  connected  to  the  bodies  of  the  vertebrae  and  the 
intervertebral  cartilages,  by  one  articulation,  and  to  the  trans- 
verse processes  of  the  vertebrae  by  another :  these  articulations 
have  the  ordinary  apparatus  for  motion,  with  capsular  ligaments, 
which  in  one  caserpass  from  the  heads  of  the  ribs  to  the  bodies 
of  the  vertebrae,  and  in  the  other  from  the  tubercles  to  the  trans- 
verse processes.  These  form  what  are  called  the  costo-vertebral, 
and  costo-transverse  articulations. 


256  ARTICULATION  OF    THE  RIBS. 

Fig.  61.*  — The  capsular  ligament  of 

the  costo-vertebral  articulation, 
is  not  complete.  It  is  much 
thickest  in  front  and  upon  the 
sides,  and  radiates  from  its  origin 
on  the  head  of  the  ribs,  whence 
it  is  usually  called  the  anterior 
radiating  or  stellate  ligament. 
— There  is  also  a  small  inter- 
articulating  ligament,  in  this 

articulation,  which  passes  from  a  ridge  on  the  head  of  the  rib  to 
a  corresponding  line  on  the  intervertebral  substance.  It  thus 
divides  the  joint  into  two  halves,  each  of  which  has  a  separate 
synovial  membrane.  This  ligament  does  not  exist  where  the 
ribs  are  attached  to  a  single  vertebra,  as  the  first,  eleventh  and 
twelfth. 

— The  costo-transverse  articulation,  besides  its  feeble  capsular 
ligament  and  synovial  membrane  connecting  the  tubercle  of  the 
rib  with  the  facet  of  the  transverse  process,  includes  three  other 
ligaments,  the  internal  transverse,  the  external  transverse,  and 
the  middle  costo-transverse. 

— The  internal  transverse,  arises  from  the  inferior  margin  of  the 
transverse  process,  and  is  inserted  into  the  upper  margin  of  the 
neck  of  the  rib  below. 

— The  external  transverse,  arises  from  the  extremity  of  the 
transverse  process,  and  is  inserted  into  the  corresponding  rib,  just 
beyond  the  tubercle. 

— The  middle  costo-transverse  ligament  is  extended  between  the 
neck  of  the  rib  and  the  contiguous  transverse  process.  To  be 
well  seen  it  is  necessary  to  saw  longitudinally  through  the  neck 
of  the  rib  and  its  transverse  process. 

These  ligaments  permit  the  motions  necessary  for  respiration, 
and  restrain  all  others. 

*  The  anterior  ligaments  of  the  vertebrae,  and  ligaments  of  the  ribs.  1.  The 
anterior  common  ligament.  2.  The  anterior  costo-vertebral  or  stellate  ligament. 
3.  The  anterior  costo-transverse  ligament.  4.  The  inter-articular  ligament  con- 
necting the  head  of  the  rib  to  the  intervertebral  substance,  and  separating  the 
two  synovial  membranes  of  this  articulation. 


HIP  JOINT. 


257 


The  connexion  of  the  ribs  anteriorly  with  their  cartilages,  is 
such  as  admits  of  no  motion  whatever  between  them  ;  but  the 
extremities  of  the  cartilages  are  articulated  with  the  sternum,  at 
the  pits  on  the  edges  of  that  bone.'  In  many  instances  there  is 
no  appearance  of  synovia  between  the  ends  of  the  cartilages  and 
the  sternum  ;  but  this  fluid  is  mostly  to  be  found  in  the  pits,  on 
the  lower  extremity  of  the  sternum. 

— In  the  articulations  between  the  cartilages  of  the  ribs  and 
the  sternum,  there  is  a  synovial  membrane,  and  two  ligaments, 
anterior  and  posterior.  These  radiate  from  the  sternal  end  of 
the  cartilage,  one  over  the  anterior,  the  other  over  the  posterior 
face  of  the  sternum,  and  are  blended  with  its  periosteum,  see 
fig.  54,  p.  245.— 

The  Hip  Joint. 

Fig.  62.*  The  acetabulum  is  lined 

with  cartilage ;  and  the 
brim  or  margin  of  it  is 
much  enlarged,  and  the 
cgvity  deepened,  by  the 
addition  of  fibro-cartilagi- 
nous  matter,  which  forms 
a  regular  smooth  edge. 
This  cartilaginous  ring  is 
continued  across  the  upper 
part  of  the  notch  in  the 
acetabulum  ;  so  that  it  com- 
pletes the  circular  margin 
of  the  cavity,  but  leaves 
the  under  part  of  the  notch 
open.  This  forms  what  is 

called  the  cotyloid  ligament.     The  head  of  the  os   femoris  is 
covered  with  cartilage,  but  the  depression   in   it   is  still  visible. 

*  The  ligaments  of  the  pelvis  and  hip-joint.  1.  The  lower  part  of  the 
anterior  common  ligament  of  the  vertebrae,  extending  downwards  over  the  front 
of  the  sacrum.  2.  The  lumbo-sacral  ligament.  3.  The  lumbo-iliac  ligament. 
4.  The  anterior  sacro-iliac  ligaments.  5.  The  obturator  membrane.  6.  Pouparl's 
ligament.  7.  Gimbernat's  ligament.  8.  The  capsular  ligament  of  the  hip-joint. 
9.  The  ilio-femoral  or  accessory  ligament. 

22* 


258  HIP  JOINT. 

From  this  depression  a  strong  round  ligametit  (ligament-urn  teres 
or  rotundum)  see  fig.  71,  p.  270,  arises,  which  appears  to  pass 
into  the  depression,  near  the  centre  of  the  acetabulum ;  but 
actually  terminates  in  the  lower  edge  of  the  cartilaginous  ring 
or  margin,  where  it  crosses  over  the  notch,  and  not  in  the  bone. 
This  ligament  is  in  fact  divided  into  two  parts  at  its  insertion  ', 
one  passes  out  at  the  inferior  .part  of  the  cotyloid  notch  and  is 
inserted  on  the  margin  of  the  ischium  ;  the  other  runs  to  the 
superior  end  of  the  notch,  and  besides  being  blended  with  the 
cotyloid  ligament,  is  attached  to  the  margin  of  the  acetabulum. 
The  thin  (synovial)  membrane  with  which  this  ligament  is 
invested  extends  to  the  centre  of  the  acetabulum,  and  has  given 
rise  to  the  opinion  that  the  ligament  was  inserted  in  the  bottom 
of  the  acetabulum.* 

This  ligament  allows  the  head  of  the  os  femoris  to  rise  out  of 
the  acetabulum,  but  it  is  probably  torn  in  every  luxation  of  the 
os  femoris. 

The  capsular  ligament,  which  contains  these  articulating 
parts,  is  the  strongest  in  the  body.  It  arises  around  the  aceta- 
bulum, near  the  basis  of  the  cartilaginous  brim,  but  it  does  not 
adhere  to  the  cartilaginous  edge  ;  and  it  is  inserted  into  the  os 
femoris,  near  the  roots  of  the  trochanters^sb  that  it  includes  a 
large  portion  of  the  neck  of  the  bone.  It  is  not  every  where  of 
the  same  thickness  and  strength  ;  for,  in  various  places,  there 
are  additional  ligamentous  fibres.  The  largest  portion  of  these 
additional  fibres  appears  to  arise  from  the  inferior  anterior  spinous 
process  of  the  ilium.  The  capsular  ligament  is  thinest  at  its 
internal  and  posterior  part. — The  additional  fibres  which  arise 
from  the  anterior  inferior  spinous  process  of  the  ilium  constitute 
the  ilio-femoral,  or  accessory  ligament. 

The  synovial  membrane  forms  the  internal  lamina  of  this 
ligament:  it  invests  the  articulating  surfaces  in  the  usual  manner, 
and  being  reflected  from  the  internal  surface  of  the  capsular 
ligament  to  the  neck  of  the  os  femoris,  it  is  in  the  place  of 
periosteum  to  that  part  of  the  bone. 

It  seems  probable  that  this  membrane  is   so  reflected   and 

*  See  motions  of  skeleton. 

^Jtejf.   <*~r      ^t-"«"  " 


ARTICULATION  OF    THE  KNEE. 

arranged,  that  the  internal  Jgament  is  covered  by  it  also,  and 
of  course,  that  this  ligament  is  exterior  to  the  synovial  mem- 
brane, j 

There  is  a  considerable  quantity  of  adipose  matter  near  the 
termination  of  the  aforesaid  internal  ligament,  which  is  also 
exterior  to  the  synovial  membrane :  some  of  this  can  be  pressed 
out  of  the  acetabulum,  at  the  vacuity  in  the  notch  under  the  car- 
tilaginous margin. 

Articulation  of  the  Knee. 

The  synovial  membrane  of  the  knee  joint  is,  in  some  places, 
without  the  support  of  a  proper  capsular  ligament,  or  external 
lamen,  so  that  it  is  easier  distinguished  in  this  articulation  than 
in  many  others. 

Fig.  63.*  It  adheres  firmly  to  the  cartilaginous  sur-. 
faces  of  the  os  femoris,  tibia,  and  patella, 
and  is  reflected  in  the  usual  manner  from 
one  to  the  other  of  these  surfaces.  It 
arises  closely  from  the  edge  of  the  cartilagi- 
nous surface  at  the  top  of  the  tibia ;  but  on 
the  anterior  part  of  the  os  femoris,  it  is 
continued  to  some  distance  from  the  mar- 
gin of  the  pulley-like  surface,  and  the  edges 
of  the  condyles.  On  each  of  the  portions 
of  the  cartilagindus  surfaces  of  the  tibia  is 
a  cartilage  of  a  semilunar  form,  so  placed 
that  its  convex  edge  rests  on  the  margin  of  the  cartilaginous 
surface,  and  its  concave  edge  is  internal.  These  cartilages  are 

*  The  right  knee  joint  laid  open  from  the  front,  in  order  to  show  the  internal 
ligaments.  1.  The  cartilaginous  surface  of  the  lower  extremity  of  the  femur 
with  its  two  condyles;  the  figure  5  rests  upon  the  external ;  the  figure  3  upon 
the  internal  condyle.  2.  The  anterior  crucial  ligament.  3.  The  posterior  crucial 
ligament.  4.  The  transverse  ligament.  5.  The  attachment  of  the  ligamentum 
mucosum  ;  the  rest  has  been  removed.  6.  The  internal  semi-lunar  fibro-carti- 
lage.  7.  The  external  fibro-cartilage.  8.  A  part  of  the  ligamentum  patellae 
turned  down.  9.  The  bursa,  situated  between  the  ligamentum  patellae  and  the 
head  of  the  tibia.  It  has  been  laid  open.  10.  The  anterior  superior  tibio-nbular 
ligament.  10.  The  upper  part  of  the  interosseous  membrane  ;  the  opening 
above  this  membrane  is  for  the  passage  of  the  anterior  tibial  artery. 


260 


ARTICULATION  OF    THE  KNEE. 


thick  at  their  external,  and  very  thin  at  their  internal  edges  ;  so 
that  they  form  two  superficial  concavities  on  the  top  of  the 
tibia. 

Their  extremities  are  attached  by  ligaments  to  the  central 
protuberance  of  the  tibia,  and  their  anterior  extremities  are  also 
connected  by  a  ligament  to  each  other. 

The  synovial  membrane  is  §o  reflected   as  to  cover  the  whole 
Fig.  64.*          surface    of    these   cartilages,   except    the 
exterior  edge,  which  is  connected  with  the 
external  ligaments  of  the  articulation. 

The  use  of  these  cartilages,  is  evidently 
to  form  concavities  on  the  top  of  the  tibia, 
for  accommodating  the  condyles  of  the  os 
femoris ;  and  upon  examination,  they 
will  not  appear  so  anomalous  as  they  do 
at  first  view,  for  there  is  a  considerable 
analogy  between  them  and  the  cartilagi- 
nous edges  of  the  glenoid  cavity  and  of  the 
acetabulum.  These  are  called  the  semi- 
lunar  cartilages.  The  internal  is  but  little 
more  than  a  semicircle ;  the  external  is  nearly  circular  in  its 
shape. 

The  patella  appears  to  project  into  the  cavity  of  the  joint, 

*  A  longitudinal  section  of  the  left  knee  joint,  showing  the  reflections  of  its 
synovial  membrane.  1.  The  cancerous  structure  of  the  lower  part  of  the  femur. 
2.  The  tendon  of  the  extensor  musclesof  the  leg.  3.  The  patella.  4.  The  liga- 
mentum  patellae.  5.  The  cancellous  structure  of  the  head  of  the  tibia.  6.  A 
bursa  situated  between  the  ligamentum  patellae  and  the  head  of  the  tibia.  7. 
The  mass  of  fat  projecting  into  the  cavity  of  the  joint  below  the  patella.  *  * 
The  synovial  membrane.  8.  The  pouch  of  synovial  membrane  which  ascends 
between  the  tendon  of  the  extensor  muscles  of  the  leg,  and  the  front  of  the 
lower  extremity  of  the  femur.  9.  One  of  the  alar  ligaments  j  the  other  has 
been  removed  with  the  opposite  section.  10.  The  ligamentum  mucosum  left 
entire  ;  the  section  being  made  to  its  inner  side.  11.  The  anterior  or  external 
crucial  ligament.  12.  The  posterior  ligament.  The  scheme  of  the  synovial 
membrane  which  is  here  presented  to  the  student,  is  divested  of  all  unnecessary 
complications.  It  may  be  traced  from  the  saculus  (at  8),  along  the  inner  sur- 
face of  the  patella ;  then  over  the  adipose  mass  (7)  from  which  it  throws  off  the 
mucous  ligament  (10)  ;  then  over  the  head  of  the  tibia,  forming  a  sheath  to  the 
crucial  ligaments  ;  thea  upwards  along  the  posterior  ligament  and  condyles  of 
the  femur,  to  the  sacculus  whence  its  examination  commenced. 


KNEE    JOINT.  261 

and  its  internal  surface  is  very  prominent  ;  around  the  margin 
of  this  surface,  and  especially  at  the  under  part  of  it,  the  adi- 
Fig.  65.*  pose  substance  found  in  joints  is  very^abun- 
dant.  On  each  side  of  the  adipose  mass, 
under  the  patella,  is  a  plait  of  the  synovial 
membrane,  called  ligamentum  alare  minus, 
and  majus  ;  and  a  process  of  the  mem- 
brane, called  ligamentum  mucosum  passes 
from  the  neighborhood  of  the  adipose 
mass  to  the  os  femoris  between  the  con- 
dyles. 

These  processes  retain  the  adipose  sub- 
stance in  its  proper  place,  during  the  motions 
of  the  joint. 

There  are  two  very  strong  ligaments,  called  the  anterior  and 
posterior  crucial,  which  arise  from  the  middle  protuberance  of 
the  tibia,  one  of  which  is  inserted  posteriorly  into  the  corner  face 
of  the  external  condyle  of  the  os  femoris,  and  the  other,  into 
the  outer  face  of  the  internal.  These  ligaments  decussate  each 
other  partially,  on  which  account  the  name  crucial  is  applied  to 
them.  They  are  in  a  state  of  tension  when  the  leg  is  extended, 
and  prevent  it  from  moving  farther  forward  :  when  it  is  bended 
they  are  relaxed.  They  add  greatly  to  the  strength  of  the 
connexion  between  the  os  femoris  and  tibia. 

These  ligaments  are  generally  supposed  to  be  in  the  cavity  of 
the  joint  ;  but  the  synovial  membrane  is  reflected  round  them  in 
such  a  manner  that  they  are  exterior  to  it. 

In  addition  to  the  crucial  ligaments,  this  articulation  has  the 
following  external  supports. 

When  the  leg  is  extended,  these  ligaments  are  tense,  they* 
therefore  prevent  rotation  in  the  extended  state:  when  the 

*  Posterior  view  of  the  ligaments  of  the  knee  joint.  1.  Posterior  ligament  of 
"Winslow,  connected  by  a  tendinous  expansion  with  2,  the  tendon  of  the  semi- 
membranous  muscle  ;  the  latter  is  cut  short.  3.  The  process  of  the  tendon, 
which  spreads  out  in  the  fascia  of  the  popliteus  muscle.  4.  A  process  which  is 
sent  inwards  beneath  the  internal  lateral  ligament.  5.  The  posterior  part  of  the 
internal  lateral  ligament.  6.  The  long  external  lateral  ligament.  7.  Short  ex- 
ternal lateral  ligament.  8.  Tendon  of  popliteus  cut  short.  9.  The  posterior 
superior  tibio-fibular  ligament. 

"  ^ 


/ 


262  KNEE    JOINT. 

leg  is    bent,   they  are  relaxed,  and,  therefore,  admit  of   that 
motion. 

1.  Two  strong  lateral  ligaments,  one  on  each  side  of  the  knee  ; 
the  external  of  which  arises  from  the  tubercle  above  the  external 
condyle  of  the  os  fernoris,  and  is  attached  to  the  fibula  a  little 
below  its    head  ;   and    the    internal,   from  the    upper  part   and 
tubercle  of  the  internal  condyle,  and  is  inserted  into  the  upper 
and  inner  part  of  the  tibia. 

2.  The  posterior   ligament  or  ligament  of   Winslow,  whose 
fibres  run  obliquely  from  the  external  condyle  to  the  back  part 
of  the  internal  side  of  the  head  of  the  tibia.     This  ligament  also 
prevents  the  leg  from  being  drawn  too  far  forwards. 

3.  The  connexion  of  the  tendons  of  the  extensor  muscles  of 
the  leg,  with  this  articulation,  has  a  great  effect  upon  it.     Their 
insertion   into  the  patella  places  them  in   the  situation  of  the 
upper  part  of  the  anterior  ligament,  of  which  the  very  strong 
ligament,  that  passes  from  the  lower  margin  of  the  patella  to  the 
tubercle  of  the  tibia,  is  only  the  lower  portion  ;  while  the  patella 
may  be  considered  as  an  inducted  part  of  the  ligament.     The 
tendons  of  the  ham-string  muscles,  also,  serve  to  strengthen  the 
articulation  on  the  back  and  sides. 

Fig.  66.*  — The  fascia  lata  of  the  thigh  as  it  passes 
down  upon  the  leg,  is  thickened  by  a  pro- 
cess of  the  extensor  tendons,  and  forms  a 
strong  external  investment  or  involucrum 
to  the  knee  joint.  It  constitutes  in  fact  a 
sort  of  capsular  ligament  to  the  joint ;  it 
closely  embraces  the  patella  and  its  liga- 
ments, covers  in  and  is  partly  blended  with 
the  lateral  ligaments,  and  is  firmly  attached 
to  the  condyles.  At  the  posterior  part  of 
the  joint,  it  forms  a  thin  membrane,  and 
can  scarcely  be  traced.  Its  place  is  there 

*  The  anterior  view  of  the  ligaments  of  the  knee  joint.  1.  The  tendon  of 
the  quadriceps  extensor  muscle  of  the  leg.  2.  The  patella.  3.  The  anterior 
ligament,  or  ligamentum  patellae,  near  its  insertion.  4,  4.  The  synovial  mem- 
brane. 5.  The  internal  lateral  ligament.  6.  The  long  external  lateral  ligament, 
7.  The  anterior  superior  tibio-fibular  ligament 


ARTICULATION  OF    THE  TIBIA  AND  FIBULA.  263 

supplied  by  the  posterior  ligament.  On  either  side  of  the  liga- 
ment of  the  patella  its  inner  face  is  in  contact  with  the  synovial 
membrane  of  the  joint. —  ; 

Bursa  Mucosa. 

There  are  two  of  these  in  connection  with  the  ligamentum 
patellae ;  one  of  which  is  placed  superficially  between  the 
ligament  and  the  fascia  lata.  This  is  the  seafrof  the  enlargement 
by  increase  of  secretion,  known  under  the  name  of  housemaid's 
knee.  The  other  is  placed  between  the  tibia  and  the  ligamentum 
patellae,  as  seen  in  fig.  66. 

Articulation  of  the  Tibia  and  Fibula. — Superior  Articulution. 

The  surfaces  of  the  upper  extremities  of  the  tibia  and  fibula, 
which  are  articulated  with  each  other,  are  very  small.  When 
the  bones  are  in  their  natural  position,  these  surfaces  are  nearly 
horizontal,  that  of  the  tibia  looking  down,  and  that  of  the  fibula 
looking  up  :  they  are  covered  with  cartilages,  and  have  a  syno- 
vial membrane.  This  articulation  is  supported  by  some  liga- 
mentous  fibres,  which  have  been  called  anterior  superior,  and 
posterior  superior  ligaments ;  it  is  strengthened  also  by  the 
external  lateral  ligament  of  the  knee,  and  by  the  tendon  of  the 
biceps  muscle  which  is  inserted  into  the  upper  end  of  the 
fibula. 

Inferior  Articulation. 

At  their  lower  extremities,  the  cartilaginous  crust,  which,  on 
each  of  them,  forms  part  of  the  articulating  surface  with  the 
astragalous,  is  turned  up  on  their  lateral  surfaces  which  are  in 
contact  with  each  other ;  so  that  a  small  portion  (equal  in 
breadth  only  to  one  sixth  of  an  inch)  of  the  contiguous  surfaces, 
is  covered  with  cartilage ;  the  other  parts  of  these  surfaces 
which  are  very  considerable,  are  attached  to  each  other  by  the 
intervention  of  fibrous  or  membranous  matter,  and  there  is 
very  little  motion  of  the  bones  on  each  other. 

There  are  very  strong  external  ligaments,  called  the  anterior 


ANKLE    JOINT. 

inferior ,  and  posterior  inferior,  which  connect 
the  fibula  to  the  tibia  ;  and  from  the  posterior 
surface  of  the  end  of  the  fibula,  a  ligament 
called  the  transverse,  passes  to  the  posterior 
part  of  the  internal  malleolus,  which  resembles 
the  marginal  ligament  of  the  glenoid  cavity 
and  acetabulum  ;  for  it  enlarges  the  articulation 
with  the  astragalus,  while  it  serves  as  a  liga- 
ment to  the  tibia  and  fibula.  There  are  some 
short,  strong  fibres  passing  below  and  between 
the  opposite  surfaces  of  the  tibia  and  fibia, 
called  the  inferior  interosseous  ligament.  ' 


Articulation  of  the  Leg,  Foot,  and  Ankle  Joint. 

It  should  be  observed  that  the  tibia  and  fibula  are  so  firmly 
connected  with  each  other  below,  that  they  may  be  considered 
as  forming  but  one  member  of  this  articulation. 

Fig.  68.f  The    varied    surfaces    formed    by 

the  tibia  and  fibula  and  their  two 
malleolar  processes,  and  by  the  as- 
tragalus with  its  two  lateral  facets, 
where  it  is  contiguous  to  them,  are 
invested  with  the  usual  apparatus  of 
articulation.  The  synovial  fluid  is 
generally  observed  to  be  very  redun- 
dant in  this  joint.  There  are  four 
ligaments  which  enter  into  this  ar- 
ticulation. 
A  triangular  band  of  fibres  called  the  internal  lateral  liga- 

*  A  posterior  view  of  the  ankle  joint.  1.  The  lower  part  of  the  interosseous 
membrane.  2.  The  posterior  inferior  ligament  connecting  the  tibia  and  fibula. 
3.  The  transverse  ligament.  4.  The  internal  lateral  ligament.  5.  The  posterior 
fasciculus  of  the  external  lateral  ligament.  6.  The  middle  fasciculus  of  the 
external  lateral  ligament.  7.  The  synovial  membrane  of  the  ankle  joint. 
8.  The  os  calcis. 

f  An  internal  view  of  the  ankle  joint.  1.  The  internal  malleolus  of  the  tibia. 
2,  2.  Part  of  the  astragalus  ;  the  rest  is  concealed  by  the  ligaments.  3.  The  os 
calcis.  4.  The  scaphoid  bone.  5.  The  internal  cuneiforme  bone.  6.  The  inter- 
nal lateral  or  deltoid  ligament.  7.  The  anterior  ligament.  8.  The  tendo  Achillis ; 
a  small  bursa  is  seen  interposed  between  this  tendon  and  the  tuberosity  of  the 
os  calcis. 


ARTICULATION  OF    THE  ASTRAGALUS  AND  OS  CALCIS.       265 

ment  passes  downwards  from  the  tibia  at  the  internal  malleolus, 
and  is  inserted  into  the  inside  of  the  astragalus,  and  also  into 
the  os  calcis  and  naviculare.  Some  of  the  fibres  are  blended 
with  those  of  the  sheath  for  the  tendon  of  the  flexor  communis ; 
and  some  of  them  have  a  radiated  arrangement,  in  consequence 
of  which  this  has  been  called  the  deltoid  ligament. 

From  the  fibula  three  ligaments  arise,  spoken  of  collectively 
as  one  ligament,  external  lateral,  (ligament-urn  triquetrum.) 
The  middle  fasciculus,  which  is  strong  and  thick,  passes  down- 
wards from  the  end  of  that  bone,  to  be  inserted  into  the  outside 
of  the  os  calcis.  The  anterior  fasciculus  passes  forwards,  and 
is  attached  to  the  astragalus.  The  posterior  fasciculus  passes 
backwards,  and  is  attached  to  the  posterior  part  of  the  astragalus. 
—The  anterior  ligament  is  a  thin  membranous  layer,  in  contact 
with  the  synovial  membrane,  it  passes  from  the  anterior  margin 
of  the  tibia  and  is  inserted  into  the  anterior  portion  of  the  astra- 
galus, near  the  articular  surface.  No  well  marked  posterior  liga- 
ment exists  at  this  articulation.  The  transverse  ligament  sup- 
plies its  place. 

Articulation  of  the  Astragalus  and  Os  Calcis. 

Fig.  69.*  The  astragalus  is  attached  firmly  to 

the*  os  calcis  by  very  strong  and 
short  ligamentous  fibres,  which  arise 
from  the  fossa  on  its  under  surface, 
and  are  inserted  into  the  fossa  Be- 
tween the  upper  articulating  sur- 
faces of  the  os  calcis.  This  is  called 
the  interosseous.  This  ligament 
separates  the  posterior  articulations 
of  the  astragalus  and  os  calcis  from 
the  anterior.  The  posterior  articulation  has  a  synovial  mem- 
brane exclusively  appropriated  to  it.  The  anterior  articulation 

*  An  external  view  of  the  ankle  joint.  1.  The  tibia.  2.  External  malleolus 
of  the  fibula.  3,  3.  Astragalus.  4.  Os  calcis.  5.  Cuboid  bone.  6.  The  ante- 
rior fasciculus  of  the  external  lateral  ligament  attached  to  the  astragalus.  7.  Its 
middle  fasciculus  attached  to  the  os  calcis.  8.  Its  posterior  fasciculus  attached 
to  the  astragalus.  9.  The  anterior  ligament  of  the  ankle. 
23 


266 


ARTICULATION  OF    THE  TARSAL    BONES. 


is  supplied  by  an  extension  of  the  membrane  which  invests  the 
articulating  surfaces  of  the  astragalus  and  naviculare. 

The  connexion  of  the  astragalus,  with  the  os  calcis  is  sup- 
ported by  the  lateral  ligaments  of  the  ankle  joint,  and  also  by 
many  irregular  ligamentous  fibres. 

Articulation  of  the  Astragalus  with  the  Os  Naviculare. 

This  articulation  appears  calculated  for  considerable  motion, 
as  well  from  the  form  of  the  two  surfaces  concerned  in  it,  as 
the  perfect  state  of  their  articulating  investments.  Their  mo- 
tions are  restrained  to  a  certain  degree,  by  ligaments,  which  are 
situated  on  the  upper  and  internal  surfaces  of  the  foot. 

Fig.  10.*  — On  the  upper   surface  of  the  foot,  is  a 

thin  broad  ligament  formed  of  parallel  and 
oblique  fibres,  stretched  from  the  upper  and 
inner  face  of  the  astragalus  to  the  upper 
surface  of  the  scaphoides  or  naviculare ; 
some  of  the  fibres  extend  even  to  the  cunei- 
forme  bones. 

— On  the  under  surface  of  the  foot,  these 
bones  are  connected  by  two  ligaments,  cal- 
caneo-scaphoid  internum,  and  externum. 
— The  internal  arises  from  the  inner  margin 
of  the  lesser  apophysis  of  the  os  calcis,  and 
runs  obliquely  forwards  and  inwards,  to  be 
inserted  on  the  inner  and  under  surface  of 
the  os  naviculare.  It  is  a  strong  ligament, 
and  contributes  much  to  the  preservation  of 
the  arched  form  of  the  foot.  On  its  under 
surface  is  a  trochlea  for  the  tendons  of  the  flexor  pollicis  and 

*  The  ligaments  of  the  sole  of  the  foot.  1.  The  os  calcis.  2.  The  astragalus. 
3.  The  tuberosity  of  the  scaphoid  bon£ .  4.  The  long  calcaneo-cuboid  ligament. 
5.  Part  of  the  short  calcaneo-cuboid  ligament.  6.  The  internal  calcaneo-sca- 
phoid  ligament.  7.  The  plantar  tarsal  ligaments.  8,  8.  The  tendon  of  the 
peroneus  longus  muscle.  9,  9.  Plantar  tarso-metatarsal  ligaments.  10. 
Plantar  ligament  of  the  metatarso-phalangeal  articulation  of  the  great  toe ;  the 
same  ligament  is  seen  upon  the  other  toes.  11.  Lateral  ligaments  of  the  meta- 
tarso-phalangeal articulation.  12.  Transverse  ligament.  13.  The  lateral  liga- 
ments of  the  phalanges  of  the  great  toe ;  the  same  ligaments  are  seen  upon  the 
other  toes. 


ARTICULATION  OF    THE  OS  CALCIS  AND  CUBOIDES.          267 

flexor  longus  digitorura.  Below  it  is  also  in  contact  with  the 
tendon  of  the  tibialis  posticus,  and  above  with  the  head  of  the 
astragalus,  which  it  in  part  supports.  y 

— The  external  is  at  the  outer  side  of  the  last ;  it  arises  from  the 
under  surface  of  the  greater  apophysis  of  the  os  calcis,  and  is 
inserted  upon  the  under  internal  surface  of  the  os  naviculare. — 

The  ligaments  which  pass  from  the  anterior  internal  extremity  of  the  os  calcis 
to  the  os  naviculare,  and  support  the  head  of  the  astragalus,  ought  to  be 
observed  with  attention  during  the  examination  of  this  joint. 

Articulation  of  the  Os  Calcis  and  Cuboides. 

The  articulating  surfaces  of  this  joint  are  arranged  in  the 
usual  manner. 

There  are  two  additional  ligaments  :  one  placed  on  the  upper, 
and  the  other  on  the  under  surfaces  of  the  bones.  The  upper 
ligament  is  thin  ;  but  the  under  ligament  is  one  of  the  strongest 
of  the  foot ;  and  its  fibres  are  blended  with  those  which  form 
the  sheath  for  the  tendon  of  the  peroneus  longus,  as  it  passes 
along  the  groove  in  the  cuboides. 

— These  ligaments  are  called  the  superior  and  inferior  calca- 
neo-cuboid.  The  latter  is  by  some  considered  as  consisting  of 
two  ligaments,  the  short  and  long. 

— The  superior  passes  from  the  upper  anterior  surface  of  the 
os  calcis  to  the  adjoining  surface  of  the  os  cuboides. 
— The  inferior  is  the  strongest  ligament  of  the  foot.  It  arises 
from  the  inferior  back  part  of  the  os  calcis,  and  part  of  its 
fibres  are  inserted  upon  the  oblique  ridge  or  the  tendon  of  the 
peroneus  longus  which  traverses  the  under  part  of  the  os  cu- 
boides. This  part  is  sometimes  called  the  short  inferior  calca- 
neo-cuboid  ligament.  The  greater  part  of  the  fibres  of  this 
ligament,  pass  beyond  the  ridge,  and  are  inserted  in  fasciculi 
upon  the  basis  of  the  third  and  fourth  metatarsal  bones.  These 
subtend  the  groove,  in  which  passes  the  tendon  of  the  peroneus 
longus  muscle,  and  constitute  the  long  inferior  calcaneo-cuboid 
ligament. 

— The  other  bones  of  the  foot  are  united  in  general  by  dorsal  and 
plantar  ligaments  like  the  corresponding  bones  of  the  hand. — 


268  PARTICULAR   LIGAMENTS, 


CHAPTER   VI. 

OF   PARTICULAR   LIGAMENTS,  AND  OF   THE    SITUATION  OF 
THE  INDIVIDUAL  BURS^E  MUCOS^E. 

Enumeration  of  the  most  important  Ligaments,  which  have  not  been  described, 

Ligaments  proper  to  the  Scapula. 

THE  triangular  ligament  (ligamentum  coraco-acromialis) 
arises  broad  from  the  external  surface  of  the  coracoid  process,, 
and  becomes  narrower  where  it  is  fixed  to  the  posterior  margin 
of  the  acromion.  It  confines  the  tendon  of  the  supra-spinatus 
muscle,  and  assists  in  protecting  the  upper  and  inner  part  of  the 
joint  of  the  humerus. 

The  posterior  ligament  of  the  scapula  (coracoid)  is  some- 
times double,  and  is  stretched  across  the  semilunar  notch  of 
the  scapula,  forming  that  notch  into  one  or  two  holes  for  the 
passage  of  the  superior  posterior  scapulary  vessels  and  nerves. 
It  also  gives  rise  to  part  of  the  omo-hyoideus  muscle. 

The  Interosseous  Ligament  of  the  Forearm, 

Extends  between  the  sharp  ridges  of  the  radius  and  ulna, 
filling  up  the  greater  part  of  the  space  between  these  two 
bones,  and  is  composed  of  small  fasciculi,  or  fibrous  slips,  which 
run  obliquely  downwards  and  inwards.  Two  or  three  of  these, 
however,  go  in  the  opposite  direction,  and  one  of  them,  termed 
oblique  ligament  and  chorda  transversalis  cubiti,  is  stretched 
between  the  tubercle  of  the  ulna  and  under  part  of  the  tubercle 
of  the  radius.  In  different  parts  of  the  ligament  there  are 
perforations  for  the  passage  of  blood-vessels  from  the  fore  to 
the  back  part  of  the  bone,  and  a  large  opening  is  found  at  the 
upper  part  of  it  which  is  filled  up  by  muscles.  It  prevents  the 
radius  from  rolling  too  much  outwards,  and  furnishes  a  com- 
modius  attachment  for  muscles. 


LIGAMENTS    OF    THE    HAND.  269 

ligaments  retaining  the  Tendons  of  the  Muscles  of  the  Hand 
and  Fingers  in  their  proper  positions. 

The  anterior  annual  ligament  of  the  wrist  is  stretched  across 
from  the  projecting  points  of  the  pisiform  and  unciform  bones, 
to  the  os  scaphoides  and  trapezium,  and  forms  an  arch  which 
covers  and  preserves  in  their  places  the  tendons  of  the  flexor 
muscles  of  the  fingers. 

The  vaginal  ligaments  of  the  flexor  tendons  are  five  mem- 
branes, connecting  the  tendons  of  the  sublimis,  first  to  each 
other,  and  then  to  those  of  the  pro  fund  us  ;  forming,  at  the  same 
time,  bursae  mucosae  which  surround  the  tendons. 

The  vaginal  or  crucial  ligaments  of  the  phalanges  arise  from 
the  ridges  on  the  concave  side  of  the  phalanges,  and  run  over 
the  tendons  of  the  flexor  muscles  of  the  fingers.  Upon  the 
body  of  the  phalanges,  they  are  thick  and  strong,  to  bind  down 
the  tendons,  but  over  the  joints  they  are  thin,  and  have,  in 
some  parts,  a  crucial  appearance,  to  allow  the  ready  motion  of 
the  joints. 

The  accessory  ligaments  of  the  flexor  tendons  of  the  fingers 
are  small  tendinous  fraena,  arising  from  the  first  and  second 
phalanges  of  the  finger.  They  run  obliquely  forwards  within 
the  vaginal  ligaments,  terminate  in  the  tendons  of  the  two  flexor 
muscles  of  the  fingers,  and  assist  in  keeping  them  in  their  places. 

The  posterior  annular  ligament  of  the  wrist  is  part  of  the 
aponeurosis  of  the  forearm,  extending  across  the  back  of  the 
wrist,  from  the  extremity  of  the  ulna  and  os  pisiforme  to  the 
extremity  of  the  radius.  It  is  connected  with  the  small  annular 
ligaments  which  tie  down  the  tendons  of  the  extensores  ossis 
metacarpi  et  primi  internodii  pollicis,  and  the  extensor  carpi 
ulnaris. 

The  vaginal  ligaments  adhere  to  the  last  mentioned,  and 
serve  as  sheaths  and  bursae  rnucosae  to  the  extensor  tendons  of 
the  hand  and  fingers. 

The    transverse    ligaments,  of    the    extensor    tendons,    are 
aponeurotic  slips  running  between  the  tendons,  near  the  heads 
of  the  metacarpal  bones,  and  retaining  them  in  their  places. 
23* 


^x 


270  LIGjyiENTS  OF    THE  STERNUM. 

Ligaments  on  the  Anterior  part  of  the  Thorax. 

The  membrane  proper  to  the  sternum  is  a  firm  expansion, 
composed  of  tendinous  fibres  running  in  different  directions, 
and  covering  the  anterior  and  posterior  surfaces  of  the  bone, 
being  confounded  with  the  periosteum. 

The  ligaments  of  the  cartilago  ensiformis  are  part  of  the 
proper  membrane  of  the  sternum,  divided  into  strong  bands, 
which  run  obliquely  from  the  under  and  forepart  of  the  second 
bone  of  the  sternum,  and  from  the  cartilages  of  the  seventh 
pair  of  ribs,  to  be  fixed  to  the  cartilago  ensiformis.  The  liga- 
ments covering  the  sternum  serve  considerably  to  strengthen 
that  bone. 

There  are  also  thin  tendinous  expansions  which  run  over 
the  intercostal  muscles  at  the  fore  part  of  the  thorax,  and  connect 
the  cartilages  of  the  ribs  to  each  other. 

Ligaments  of  the  Bones  of  the  Pelvis. 

Articulations  of  the  vertebral  column  with  the  pelvis.  The 
lowermost  lumbar  vertebra  is  articulated  with  the  sacrum  in  the 
same  manner  as  the  vertebrae  are  articulated  with  each  other, 
viz.,  by  the  common  anterior  and  posterior  ligaments  of  the 
spinal  column,  intervertebral  substance,  yellow  elastic  liga- 
ments, capsular  ligaments  covering  the  oblique  processes,  and 
the  interspinal  ligaments.  Two  other  ligaments  connecting  it 
with  the  bones  of  the  pelvis,  are  denominated  the  ilio  lumbar  or 
lumbo-iliac  ligament,  and  the  sacro-vertebral  or  lumbar  sacral 
ligament.  From  their  direction  they  are  sometimes  called  the 
two  transverse  ligaments  of  the  pelvis. 

The  ilio-lumbar,  (see  fig.  62,  p.  257,)  arises  from  the  point  of 
the  transverse  process  of  the  last  lumbar  vertebra,  and  from 
the  oblique  process  below  and  is  inserted  for  about  two  inches 
into  the  crest  of  the  ileum  just  above  its  posterior  superior 
spinous  process.  It  sometimes  from  being  blended  with  adipose 
substances  presents  the  appearance  of  two  distinct  ligaments. 

The  sacro-vertebral,  arises  from  the  under  part  of  the  trans- 
verse process  of  the  last  lumbar  vertebra,  and  is  inserted  into 


LIGAMENTS  OF  THE  STERNUM.  271 

the  upper  part  of  the  base  of  the  sacrum  near  the  anterior  liga- 
ment of  the  sacro-iliac  articulation  with  which  some  of  its  fibres 
are  blended.  y 

The  proper  ligaments  of  the  pelvis,  are  as  follows,  viz.  1. 
Those  which  connect  the  ilium  and  sacrum.  2.  Those  between 
the  sacrum  and  ischium.  3.  Those  between  the  sacrum  and 
coccyx,  and  4.  Those  which  join  the  two  pubic  bones  together. 

1.  Ligaments  connecting  the  Ilium  and  Sacrum. 

A  long  flat  ligament  called  the  sacro-spinous  (lig.  sacro- 
spinosum)  arises  from  the  posterior  superior  spinous  process 
of  the  os  ilium  descends  obliquely  and  is  inserted  into  the  third 
and  fourth  transverse  processes  of  the  sacrum.  It  sometimes 
presents  the  appearance  of  two  separate  ligaments. 

The  ligaments  which  form  the  sacro-iliac  junction  are  two 
in  number,  and  are  called  anterior  and  posterior. 
— The  anterior  sacro-iliac  ligament,  consists  of  a   thin  plane 
of  short,  strong  ligamentous  fibres,  passing  from  bone  to  bone  on 
the  anterior  face  of  the  joint. 

The  posterior  sacro-iliac  ligament,  is  the  main  stay  of  the 
articulation.  It  consists  of  many  strong  bundles  of  ligamentous 
fibres,  which  cross  horizontally  over  the  posterior  part  of  the 
joint,  and  are  attached  by  one  extremity  to  the  rough  surface  of 
the  ilium  immediately  behind  the  joint,  and  by  the  other  to 
two  eminences  on  the  lateral  margin  of  the  sacrum,  as  well  as 
the  rough  surfaces  of  the  bone  between  them. 

2.  Ligaments  connecting  the  Sacrum  and  Ischium. 

The  two  sacro-ischiatic  ligaments,  see  fig.  71,  are  situated  in 
the  under  and  back  part  of  the  pelvis.  They  arise  nearly  in 
common  from  the  transverse  processes  of  the  os  sacrum,  from 
the  under  and  lateral  part  of  that  bone,  and  from  the  upper  part 
of  the  os  coccygis.  The  first,  called  the  external  posterior  or 
greater,  descends  obliquely,  to  be  fixed  to  the  tuberosity  of 
the  os  ischium.  The  other,  called  the  lesser,  internal  or  ante- 
rior sacro-sciatic  or  sacro-ischiatic  ligament,  runs  transversely 
to  be  fixed  to  the  spinous  process  of  the  os  ischium.  These 


272 


LIGAMENTS    OF    THE    PELVIS, 


two  ligampnts  assist  in  binding  the  bones  of  the  pelvis,  in  sup- 
porting its  contents,  and  in  giving  origin  to  part  of  its  muscles. 
Fig.    71.*  There  are  two  membra- 

nous productions  which 
are  connected  with  the 
large  sacro-ischiatic  liga- 
ment, termed  its  superior 
and  inferior  appendices. 

The  superior  appendix, 
which  is  tendinous,  arises 
from  the  back  part  of  the 
os  ilium,  and  is  fixed  along 
the  outer  edge  of  the  liga- 
ment, which  it  increases  in 
breadth. 

The  inferior  or  falci- 
form appendix,  situated 
within  the  cavity  of  the 
pelvis,  the  back  part  of  which  is  connected  with  the  middle 
of  the  large  external  ligament,  and  the  rest  of  it  is  extended 
round  the  curvature  of  the  os  ischium. 

These  two  productions  assist  the  large  sacro-ischiatic  liga- 
ment in  furnishing  a  more  commodious  situation  for,  and 
insertion  of,  part  of  the  gluteus  maximus,  and  obturator 
internus  muscles. 

The  large  holes  upon  the  back  part  of  the  os  sacrum  are 
also  surrounded  with  various  ligamentous  expansions,  pro- 
jecting from  one  tubercle  to  another,  and  giving  origin  to  mus- 
cular fibres,  and  protection  to  small  vessels  and  nerves  which 
creep  under  them. 


*  Ligaments  of  the  pelvis  and  hip-joint.  The  view  is  taken  from  the  side. 
1.  The  oblique  sacro-iliac  ligament.  The  other  fasciculi  of  the  posterior  sacro- 
iliac  ligaments  are  not  seen  in  this  view  of  the  pelvis.  2.  The  posterior  sacro- 
ischiatic  ligament.  3.  The  anterior  sacro-ischiatic  ligament.  4.  The  great 
sacro-ischiatic  foramen.  5.  The  lesser  sacro-ischiatic  foramen.  6.  The  coty- 
loid  ligament  of  the  acetabulum.  7.  The  ligamentum  teres.  8.  The  cut  edge 
of  the  capsular  ligament,  showing  its  extent  posteriorly  as  compared  with  its 
anterior  attachment.  The  obturator  membrane  only  partly  seen. 


LIGAMENTS    OF    THE    PELVIS.  273 

3.  Ligaments  connecting  the  Sacrum  and  Os  Coccygis. 

A  general  covering  is  sent  down  from  the  ligaments  of  the 
os  sacrum,  which  spreads  over  and  connects  the  different  pieces 
of  the  os  coccygis  together,  allowing  considerable  motion,  as 
already  mentioned,  in  the  description  of  this  bone.  This 
forms  what  is  called  the  anterior  and  posterior  coccygeal  lig- 
aments. 

The  posterior  longitudinal  ligaments  of  the  os  coccygis 
descend  from  those  upon  the  dorsum  of  the  os  sacrum,  to  be 
fixed  to  the  back  part  of  the  os  coccygis.  The  ligaments  of 
this  bone  prevent  it  from  being  pulled  too  much  forwards  by 
the  action  of  the  coccygeus  muscle,  and  they  restore  the  bone 
to  its  natural  situation,  after  the  muscle  has  ceased  to  act. 

4.  Ligaments  connecting  the  Ossa  Pubis. 

A  ligamentous  Jibro-cartilage,  resembling  in  structure  the 
intervertebral  substance,  unites  the  two  ossa  pubis  so  firmly 
together  at  their  symphysis  as  to  admit  of  no  motion,  excepting 
in  the  state  of  pregnancy,  when  it  is  frequently  found  to  be  so 
much  softened  as  to  yield  a  little  in  the  time  of  delivery.  ^ 

— There  are  a  few  transverse  ligamentous  fibres  on  the  front 
part  of  the  symphysis  pubis,  called  the  anterior  pubic  ligament. 
These  interlace  in  front  of  the  symphysis. 
— There  are  also  a  few  irregular  fibres  on  the  posterior  face 
of  the  articulation  crossing  from  bone  to  bone,  called  the  poste- 
rior pubic  ligament. 

— The  sub,  or  interpubic  ligament  occupies  the  summit  of  the 
arch  of  the  pubis.  It  is  about  half  an  inch  in  breadth,  and 
passes  from  the  crus  of  the  pubis  of  one  side  to  that  of  the 
other. — 

— A  thick  strong  band  of  fibres  is  found  crossing  from  bone  to 
bone,  on  their  superior  face,  and  filling  up  the  inequalities 
which  exist  there  ;  it  is  called  the  superior  pubic  ligament. 

The  obturator  membrane,  or  ligament  of  the  foramen  thy- 
roideum,  adheres  to  the  margin  of  the  foramen  thyroideum,  and 
fills  the  whole  of  that  opening,  excepting  the  oblique  notch  at 


274  LIGAMENTS   OF    THE  FOOT. 

its  upper  part  for  the  passage  of  the  obturator  vessels  and  nerve. 
It  assists  in  supporting  the  contents  of  the  pelvis,  and  in  giving 
origin  to  the  obturator  muscles.  See  fig.  62,  p.  257. 

The  interosseous  ligament  of  the  kg  fills  the  space  between 
the  tibia  and  fibula  like  the  interosseous  ligament  of  the  forearm, 
and  is  of  a  similar  structure ;  being  formed  of  the  oblique  fibres, 
and  perforated  in  various  plaoes  for  the  passage  of  vessels  and 
nerves. 

At  the  upper  part  of  it  there  is  a  large  opening,  where  the 
muscles  of  the  opposite  sides  are  in  contact ;  and  where  vessels 
and  nerves  pass  to  the  fore  part  of  the  leg. 

It  serves  chiefly  for  the  origin  of  part  of  the  muscles  which 

belong  to  the  foot. 

» 

Ligaments  retaining  the  Tendons  of  the  Muscles  of  the  Foot 
and  Toes  in  their  proper  position. 

The  annular  ligament  of  the  tarsus  is  a  thickened  part  of 
the  aponeurosis  of  the  leg,  splitting  into  superior  and  inferior 
portions,  which  bind  down  the  tendons  of  the  extensors  of  the 
toes  upon  the  forepart  of  the  ankle. 

The  vaginal  ligament  of  the  tendons  of  the  peronei  muscles, 
behind  the  inkle  is  common  to  both,  but  divides  at  the  outer 
part  of  the  foot,  and  becomes  proper  to  each.  They  preserve 
the  tendons  in  their  places,  and  are  the  bursae  of  these  tendons. 

The  laciniated  ligament  arises  from  the  inner  ankle,  and 
spreads  in  a  radiated  manner,  to  be  fixed  partly  in  the  cellular 
substance  and  fat,  and  partly  to  the  os  calcis,  at  the  inner  side 
of  the  heel.  It  encloses  the  tibialis  posticus  and  flexor  digitorum 
longus. 

The  vaginal  ligament  of  the  tendon  of  the  extensor  proprius 
pollicis  runs  in  a  crucial  direction. 

The  vaginal  ligament  of  the  tendon  of  the  flexor  longus 
pollicis  surrounds  this  tendon  in  the  hollow  of  the  os  calcis. 

The  vaginal  and  crucial  ligaments  of  the  tendons  of  the  flexors 
of  the  toes  inclose  these  tendons  on  the  surfaces  of  the  pha- 
langes, and  form  their  bursae  mucosae. 

The  accessory  ligaments  of  the  flexor  tendons  of  the  toes,  as  in 


BURSJE    MUCOS.E.  275 

the  fingers,  arise   from  the   phalanges,  and   are  included  in  the 
sheaths  of  the  tendons  in  which  they  terminate. 

The  transverse  ligaments  of  the  extensor  tendons  run  between 
them,  and  preserve  them  in  their  places  behind  the  roots  of 
their  toes. 

Enumeration  of  the  most  important  Bursse  Mucosae. 
Those  about  the  articulation  of  the  Shoulder  are  situated, 

1.  Under  the  clavicle,  where  it  plays  upon  the  coracoid  pro- 
cess. 

2.  Between  the  triangular  ligament  of  the  scapula  and  the 
capsular  ligament  of  the  humerus. 

3.  Between  the  point  of  the  coracoid  process  and  capsular 
ligament  of  the  humerus. 

4.  Between  the  tendon  of  the  subscapiilaris  muscle  and  cap- 
sular ligament  of  the  humerus,  frequently  communicating  with 
the  cavity  of  that  joint. 

5.  Between    the  origin   of   the  coraco-brachialis  and    short 
head  of  the  biceps  muscles,  and  capsular  ligament  of  the  hu- 
merus. 

6.  Between  the  tendon  of  the  teres  major  and  the  os  humeri, 
and  upper  part  of  the  tendon  of  the  latissimus  dorsi. 

7.  Between    the    tendon    of    the   latissimus    dorsi   and    os 
numeri. 

8.  Between  the  tendon  of  the  long  head  of  the  biceps  flexor 
cubiti  and  the  humerus. 

The  Bursae  marked  3  and  5  are  sometimes  absent. 
Near  the  articulation  of  the  Elbow  there  are, 

1.  With  a  peloton  of  fat,  between  the  tendon  of  the  biceps 
an^  tubercle  of  the  radius. 

2.  Between  the  tendon  common  to  the  extensor  carpi  radialis 
brevier,  extensor  digitorum  communis,  and  round  head  of  the 
radius.         • 

3.  A  small  bursa,  between  the  tendon  of  the  triceps  extensor 
cubiti  and  olecranon. 


276  BURSJE   MUCOSJE  OF    THE  UPPER    EXTREMITY. 

On  the  Forearm  and  Hand  are  situated, 

1.  A  very  large  bursa  surrounding  the  tendon  of  the  flexor 
pollicis  longus. 

2.  Four  long  bursae  lining  the  sheaths  which    enclose   the 
tendons  of  the  flexors  upon  the  fingers. 

3.  Four  short  bursae  on  the  forepart  of  the  tendons  of  the 
flexor  digitorum  sublimis  in  tlfe  palm  of  the  hand. 

4.  A  large  bursa  between  the  tendons  of  the  flexor  pollicis 
longus,  the  forepart  of  the  radius,  and  capsular  ligament  of  the 
os  trapezium. 

5.  A  large  bursa  between  the  tendons  of  the  flexor  digitorum 
profundus,  and  the  forepart  of  the  end  of  the  radius,  and  capsu- 
lar ligament  of  the  wrist. 

These  two  last  mentioned  bursse  are  sometimes  found  to  communicate  with 

each  other. 

7.  A  bursa  between  the  tendon  of  the  flexor  carpi  radialis 
and  os  trapezium. 

8.  Between  the  tendon  of  the  flexor  carpi  ulnaris  and  os 
pisiforme. 

9.  Between  the  tendon  of  the  extensor  ossis  metacarpi  pollicis 
and  radius. 

10.  A  large  bursa  common  to  the  extensores  carpi  radiales, 
where  they  cross  behind  the  extensor  ossis  metacarpi  pollicis. 

11.  Another  common  to  the  entensores  carpi  radiales,  where 
they  cross  behind  the  extensor  secundi  internodii  pollicis. 

12.  A  third,  at  the  insertion  of  the  tendon  of  the  extensor 
carpi  radialis  brevior. 

13.  A  bursa  for  the  tendon  of  the  extensor  secundi  internodii 
pollicis,  which  communicates  with  the  second  bursa  common  to 
the  extensores  carpi  radiales. 

14.  Another  bursa  between  the  tendon  of  the  extensor  secun- 
di internodii  pollicis  and  metacarpal  bone  of  the  thumb.         t 

15.  A  bursa  between  the  tendons  of  the  extensor  of  the  fore, 
middle,  and  ring  fingers,  and  ligament  of  the  wrist. 

16.  For  the  tendons  of  the  extensor  of  the  little  finger. 

17.  Between  the  tendon  of  the  extensor  carpi  ulnaris  and 
ligament  of  the  wrist. 


BURSJE  MUCOSJE  OF    THE  THIGH    AND  ANKLE.  277 

Upon  the  Pelvis  and  upper  part  of  the  Thigh  there  are, 

1 .  A  very  large  bursa  between  the  iliacus  internus  and  psoas 
rnagnus  muscles,  and  the  capsular  ligament  of  the  thigh  bone. 

2.  One  between  the  tendon  of  the  pectinalis  muscle  and  the 
thigh  bone. 

3.  Between   the  gluteus  medius  and   trochanter  major,  and 
before  the  insertion  of  the  tendon  of  the  pyriformis. 

4.  Between  the  tendon  of  the  gluteus  minimis  and  trochanter 
major. 

5.  Between  the  gluteus  maximus  and  vastus  externus. 

6.  Between  the  gluteus  medius  and  pyriformis. 

7.  Between  the  obturator  internus  and  os  ischium. 

8.  An  oblong  bursa  continued  a  considerable  way  between  the 
obturator  internus,  gemini,  and  capsular  ligament  of  the  thigh 
bone.  % 

9.  A  small  bursa  at  the  head  of  the  semimembranosus  and 
biceps  flexor  cruris. 

10.  Between  the  origin  of  the  semitendinosus  and  that  of  the 
two  former  muscles. 

11.  A  large  bursa  between  the  tendon  of  the  gluteus  maximus 
and  root  of  the  trochanter  major. 

12.  Two  small  bursae  between  the  tendon   of   the  gluteus 
maximus  and  thigh  bone. 

About  the  Joint  of  the  Knee  are, 

1.  A  large  bursa  behind  the  tendon  of  the  extensors  of  the 
leg,  frequently   found   to  communicate  with   the  cavity  of  the 
knee  joint. 

2.  Behind  the  ligament  which  joins  the  patella  to  the  tibia, 
in  the  upper  part  of  the  cavity  of  which  a  fatty  substance 
projects. 

3.  Between  the  tendons  of  the  sartorius,  gracilis,  semitendi- 
nosus, and  tibia. 

4.  Between  the  tendons  of  the  semimembranosus  and  gemel- 
lus,  and  ligament  of  the  knee.     This  bursa  contains  a  small  one 
within  it,  from  which  a  passage  leads  into  the  cavity  of  the  joint 
of  the  knee. 

24 


278  BURSJE  MUCOS.ZE  OF    THE   ANKLE  AND  FOOT. 

5.  Between    the    tendon   of   the  semimembranosus   and  the 
internal  lateral  ligament  of  the  knee,  from  which  also  there  is  a 
passage  leading  into  the  joint  of  the  knee. 

6.  Under  the  popliteus  muscle,  likewise  communicating  with 
the  cavity  of  the  knee  joint. 

About  the  pinkie  there  are, 

1.  A  bursa  between  the  tendon  of  the  tibialis  anticus,  and 
under  part  of  the  tibia  and  ligament  of  the  ankle. 

2.  Between  the  tendon  of  the  extensor  proprius  pollicis  pedis, 
and  the  tibia  and  capsular  ligament  of  the  ankle. 

3.  Between   the   tendons  of  the   extensor   digitorum   longus, 
and  ligament  of  the  ankle. 

4.  Common  to  the  tendons  of  the  peronei  muscles. 

5.  Proper  to  the  tendon  of  the  peroneus  brevis. 

6.  Between  the  tendon  achillis  and  os  calcis,  into  the  cavity 
of  which  a  peloton  or  mass  of  fat  projects. 

7.  Between  the  os  calcis  and  flexor  pollicis  longus. 

8.  Between  the  flexor  digitorum  longus  and  the  tibia  and  os 
calcis. 

9.  A  bursa  between  the  tendon  of  the  tibialis  posticus  and 
the  tibia  and  astragalus. 

On  the  Sole  of  the  Foot  are  also, 

1.  A  second  bursa   for  the   tendon  of  the   peroneus   longus, 
with  an  oblong  peloton  of  fat  within  it. 

2.  One  common  to  the  tendon  of  the  flexor  pollicis  longus, 
and  that  of  the  flexor  digitorum  profundus,  at  the  upper  end  of 
which  a  fatty  substance  projects. 

3.  Another  for  the  tendon  of  the  tibialis  posticus. 

4.  Several  for  the  tendons  of  the  flexors  of  the  toes. 


PART   III. 
M  Y  O  L  O  G  Y. 

CHAPTER   VII. 

GENERAL  ANATOMY  OF  MUSCLES  * 

THAT  soft,  fibrous,  red-colored  substance,  which  constitutes 
so  large  a  proportion  of  the  volume  of  the  more  perfect  ani- 
mals, is  called  Flesh  or  Muscle. 

By  the  contraction  of  this  substance,  the  spontaneous  mo- 
tions of  animals  are  produced ;  and,  on  this  account  the  fibres 
which  compose  it  have  long  been  regarded  with  particular 
attention. 

Muscular  fibres  are  not  only  arranged  in  those-  regular 
masses  on  the  trunk  and  limbs  of  the  body,  which  are  so  fami- 
liar to  us  by  the  name  of  muscles,  but  they  also  exist  in  some 
of  the  most  important  viscera,  and  produce  the  internal,  as  well 
as  the  external  motions  of  animals. 

— Muscles  have  been  divided  in  man,  and  the  superior  ani- 
mals, into  two  classes.  The  first  class  consists  of  those  which 
produce  the  external  motions  of  the  body,  and  are  placed 
exteriorly  ;  these  contract  under  the  influence  of  the  will,  are 
the  agents  by  which  are  executed  the  animal  or  voluntary  func- 
tions which  place  the  animal  in  relation  with  the  exterior 
world,  and  are  called  the  muscles  of  animal  life,  muscles  of  the 
life  of  relation,  voluntary  muscles,  etc.  These  form  by  far  the 
largest  portion  of  the  whole  mass,  and  are  attached  in  general, 
by  one  or  both  extremities  to  the  skeleton.  They  are  solid, 

*  Muscles  were  first  named  according  to  their  figure  and  situation,  in  1587, 
by  Jacques  Dubois,  surnamed  Sylvius,  a  member  of  the  Faculty  of  Medicine,  in 
Paris. — H. 


280  GENERAL  ANATOMY  OF    MUSCLES. 

that  is,  have  no  cavity  in  their  interior,  and  vary  much  in  their 
size.  The  second  class  consists  of  those  placed  in  the  interior 
of  the  body,  and  which  effect  the  movements  requisite  in  the 
various  processes  of  nutrition  and  generation.  These  are  not 
under  the  control  of  the  will,  and  are  called  the  muscles  of 
organic  life,  muscles  of  the  life  of  nutrition,  involuntary  muscles, 
etc.  They  are  generally  membraniform,  and  assist  in  forming 
the  hollow  organs,  as  in  the  heart,  digestive  canal,  uterus  and 
bladder.  With  the  exception  of  those  of  the  heart,  the  fibres 
of  this  class  of  muscles  are  of  a  pale  color,  and  some  entirely 
colorless.  A  few  of  the  muscles  of  animal  life,  as  those  of  the 
ears  and  some  of  those  of  the  face,  are  likewise  faintly  colored, 
and  are  considered  by  Isenflam,*  as  existing  even  in  the  adult 
in  a  state  of  rudimental  development,  as  their  color  and  func- 
tions are  found  much  more  fully  manifested  in  some  quadru- 
peds.! 

— The  muscles  in  the  inferior  grades  of  animals  appear  to  exist 
in  a  rudimental  condition,  and  become  more  and  more  nume- 
rous, and  of  a  color  more  and  more  red  generally,  as  we 
advance  upwards  from  the  zero  point  of  the  animal  scale.  In 
the  development  of  the  human  foetus  they  seem  to  undergo 
analogous  changes. 

— They  present  themselves  during  the  three  first  months  of 
foetal  life,  as  gelatinous  or  viscous  masses,  very  slightly  tinged 
with  yellow,  and  with  thin  tendons,  according  to  Isenflam, 


*  Anatomische  Untersuchungen,  by  H.  F.  Isenflam,  Professor  at  the  Uni- 
versity of  Dorpat. 

f  This  physiological  division  of  the  muscles  into  two  classes,  after  Bichat,  is 
eminently  useful  to  the  student,  in  enabling  him  to  simplify  and  generalize  his 
studies  of  the  muscular  system  ;  one  class  is  not,  however,  wholly  separate 
from  the  other.  Between,  is  interposed  another  subdivision  of  muscles,  called 
the  Respiratory  of  Sir  C.  Bell,  which  with  the  muscles  of  the  pharynx  and 
oesophagus,  might  be  considered  as  a  third  or  mixed  class  of  muscles,  as  they 
execute  certain  motions  involuntarily  and  unconsciously  to  the  individual,  and 
yet  are  under  the  influence  of  the  will  to  perform  motions  for  other  purposes  or 
to  execute  the  same  motions  more  rapidly  or  more  slowly.  Thus,  for  instance, 
the  muscles  of  respiration  which  carry  on  the  process  of  breathing  during  sleep, 
produce  involuntary  sneezing,  coughing  and  crying;  and  when  placed  under 
the  influence  of  the  will  are  made  to  elicit  the  voice,  etc. — P. 


GENERAL  ANATOMY  OF  MUSCLES.  281 

already  apparent  in  the  flexors  and  extensors  of  the  fingers  and 

toes. 

— At  the  end  of  the  fourth  or  fifth  month,  the  muscles  present 

a  reddish  aspect,  and   at   the  period  of  birth,  though  they  may 

be  readily  dissected  from  each  other,  they  are  very  soft,  and  of 

a  color  much  less  deep  than  those  of  the  adult, — 

Muscular  fibres  are  connected  to  each  other  by  cellular  mem- 
brane. This  membrane  surrounds  each  muscle;  and  its 
various  lamina,  gradually  diminishing  in  thickness,  pass  be- 
tween the  different  bundles  of  fibres,  and  the  different  fibres  of 
which  each  muscle  is  composed. 

The  fibres  of  muscles,  when  examined  with  magnifying 
glasses,  appear  to  be  composed  of  fibrillae  still  smaller  ;  and  it 
has  been  supposed  that  this  division  of  them  extended  beyond 
our  powers  of  vision,  even  when  assisted  by  microscopes :  but 
so  many  errors  have  occurred  in  microscopical  observations  of 
very  minute  objects,  and  so  much  difference  exists  between  the 
reports  of  different  observers,  that  the  subject  at  this  time  does 
not  interest  many  persons  ;  and  very  little  attention  is  paid,  by 
the  anatomists  and  physiologists  of  the  present  day,  to  the 
opinions  of  those  observers  who  supposed  they  had  ascertained 
the  structure  of  the  ultimate  fibrillae. 

— The  cellular  or  recticular  membrane  investing  the  whole 
muscle,  is  called  the  muscular  sheath.  It  is  formed  round 
every  muscle  of  the  body,  but  varies  much  in  different  places 
in  regard  to  thickness  and  strength.  Each  of  the  many  larger 
fasciculi)  or  bundles  of  fibres,  (lacerti,)  of  which  every  muscle 
is  obviously  composed,  is  surrounded  in  like  manner  by  pro- 
cesses sent  inwards  from  the  sheath,  and  is  a  perfect,  though 
diminutive  representative  of  the  entire  muscle. 
— This  secondary  sheath  surrounding  the  fasciculi,  sends  pro- 
cesses likewise  inwards,  and  invests  and  separates  the  indivi- 
dual fibres  so  called,  or  rather  the  primitive  fasciculi,  of  which 
each  larger  fasciculus  is  formed.  These  fibres  or  primitive 
fasciculi  themselves  are  again  susceptible  of  subdivision  into 
what  are  called  the  ultimate  muscular  filaments,  between 
which,  it  is  probable,  though  not  susceptible  of  demonstration, 
24* 


282  STRUCTURE   OF  MUSCULAR  FIBRES. 

the  elementary  particles  of  cellular  tissue  likewise  pass.  In- 
the  muscles  of  organic  life,  the  cellular  tissue  is  less  abundant, 
but  more  dense  than  in  those  of  animal  life.  In  some  parts, 
especially  in  the  digestive  canal  it  is  so  dense  and  resistant  as 
to  represent  a  sort  of  ligamentous  tissue,  and  give  attachment 
to  muscular  fibres. 

— This  delicate  sheath  surrounding  the  primary  fasciculus,  has 
been  designated  by  Mr.  Bowman  as  the  sarcolemma,  or  the 
primitive  cellular  investment  of  the  muscular  fibres. — The  term 
myolemma  has  been  applied  to  the  same  structure  by  Mr.  Wil- 
son and  Dr.  Quain. 

— The  entire  muscle  thus  appears  naturally  susceptible  of  three 
subdivisions.  1st.  Into  fasciculi,  or  bundles  of  fibres.  These 
are  the  minutest  subdivisions  which  can  be  made  with  the 
naked  eye,  without  resort  to  boiling  or  other  mechanical  means. 
These  are  themselves  collected  into  bundles,  by  septa  which 
pass  in  from  the  general  sheath  of  the  muscles,  but  which  are 
easily  unraveled  by  a  little  dissection ;  so  that  what  is  at  first 
sight  mistaken  by  the  student  for  a  fasciculus,  is  in  reality  a 
bundle  of  fasciculi.  The  size  of  each  of  these  fasciculi,  varies 
in  the  different  mtiscles  of  the  body,  and  occasionally  in  the 
same  muscle,  according  to  the  number  of  fibres  of  which  it  is 
composed.  2nd.  Into  fibres  so  called  or  the  primitive  fasciculi. 
These  are  rendered  very  apparent  by  boiling,  as  seen  daily  in 
culinary  preparations,  by  which  the  muscular  fibre  is  swoln, 
while  the  cellular  envelop,  at  the  same  time  softened  and 
reduced  to  a  gelatinous  pulp,  is  readily  burst.  These  fibres 
also  vary  in  their  thickness,  some  having  a  diameter  three  or 
four  times  as  great  as  that  of  others,  depending  upon  the  num- 
ber of  elementary  filaments — usually  amounting  to  several  hun- 
dred— of  which  it  is  composed.  3d.  Into  the  elementary,  or 
ultimate  muscular  filaments.  These  are  wholly  microscopical, 
are  not  uniform  in  their  diameter  in  all  muscles,  (those  of  organic 
life  being  much  smaller,)  and  vary  considerably  in  the  numbers 
taken  to  constitute  the  muscular  fibres  of  different  size.*  Each 

*  Meckel.  torn.  i.  p.  378. 


STRUCTURE  OF  MUSCULAR  FIBRES.  283 

of  the  muscular  fibres,  and  also,  each  of  the  ultimate  filaments, 
according  to  Prochaska  and  Rudolphi,  extend  the  whole  length 
of  the  fleshy  part  of  the  muscles,  differing  entirely  in  this  respect 
from  the  ultimate  structure  of  the  bones. 

— Anatomists  do  not  agree  in  regard  to  the  diameter  assigned 
the  ultimate  muscular  filament,  and  from  its  microscopical 
diminutiveness  any  measurement  can  be  considered  as  little 
more  than  an  approximation.  They  have  been  examined  by 
Hook,  Lewenhoeck,  Dehayde,  Muys,  and  more  recently  still  by 
Prochaska  and  others.  According  to  Prochaska,  they  are 
generally  straight  and  parallel  with  each  other,  flattened  or 
prismatic,  and  of  a  diameter  one-fifth  of  that  of  the  red  globules 
of  blood.  Autenreith  supposed  them  equal  to  one-third  of  the 
diameter.  Prevost  and  Dumas  found  them  by  their  measure- 
ment, ^th  part  of  an  inch  in  diameter,  five  or  six  times 
smaller  than  the  red  globules  of  the  blood,  and  nearly  equal, 
as  Miiller  also  has  asserted,  to  the  diameter  of  the  chyle 
globules,  or  to  the  central  nuclei  of  the  red  globules  of  blood, 
which  may  be  considered  the  most  minute  compound  constitu- 
ents of  the  economy. 

— The  more  recent  microscopical  measurements  of  Henle,  Lauth, 
Ficinis,  Bruns  and  others,  agree  in  giving  to  the  ultimate  or 
elementary  muscular  filament  of  animal  life,  a  diameter  of  Tgooo^h 
part  of  an  inch.  The  diameter  of  the  primitive  fasciculus,  com- 
monly called  muscular  fibre,  which  is  cylindrical  in  shape,  is 
considered  upon  an  average  about  Jsth  part  of  an  inch  in  diame- 
ter. Each  one  is  marked  by  striae  or  streaks,  which  pass  trans- 
versely round  them,  in  slightly  curved  or  wavy  parallel  lines 
from  fl^gg  to  T2oootn  °f  an  incn  apart. 

— The  nature  of  these  striae  which  belong  solely  to  the  mus- 
cles of  animal  life,  are  not  well  understood,  whether  they  be 
delicate  fibres  wound  round  the  primary  fasciculi,  mere  wrinkles 
in  its  myolemma  or  sheath,  or  what  seems  more  likely,  depres- 
sions corresponding  with  the  breaks  between  the  globules  or 
granules,  which,  appended  end  to  end,  constitute  a  primitive 
filament.  According  to  the  microscopical  observations  of  Messrs. 


284  STRUCTURE  OF  MUSCULAR  FIBRES. 

Bowman  and  Wilson  each  ultimate  fibril  of  animal  life  is  com- 
posed of  a  succession  of  cells,  united  by  their  flat  surfaces,  each 
cell  filled  with  a  transparent  substance,  the  essential  element  of 
the  muscle,  termed  by  Mr.  Wilson  myoline.  The  development 
of  muscular  fibre  is  supposed  to  take  place  by  the  intuitive 
formation  of  cell  germs,  out  of  an  original  plastic  deposit,  a  sort 
of  soil  for  the  germs  or  cytoblaets,  called  the  blastema. 
— The  primitive  fasciculus,  or  muscular  fibre  of  organic  life, 
which  is  solely  under  the  influence  of  the  ganglionic  nervous 
system,  is  paler  and  softer  than  those  of  animal  life  ;  is  not  so 
regularly  arranged  in  a  longitudinal  and  parallel  direction ; 
and  is  less  easily  divided  into  its  primitive  filaments.  Though 
each  fibre  is  round  if  singly  examined,  the  bundles  which  they 
form  are  flattened,  composing  muscular  membranes,  often  two 
or  three  layers  deep,  the  bundles  crossing  each  other  at  differ- 
ent angles,  and  forming  networks  and  gratings.  The  most 
remarkable  character  of  the  organic  muscular  fibre,  is  the 
existence  in  it  here  and  there  of  swellings  somewhat  larger 
than  the  diameter  of  the  fibre,  and  produced  by  the  nuclei  of 
the  original  nucleated  cells  from  which  the  fibre  was  devel- 
oped.*— 

These  fibrills  have  been  represented  as  simple  hollow  tubes, 
as  a  series  of  globular  vesicles,  as  continuations  of  arteries,  as 
termination  of  nerves,  as  structures  of  rhomboidal  bodies,  and 
finally,  as  cellular.f 

It  is  supposed  by  one  of  the  latest  observers,  who  appears  to 
be  entitled  to  great  attention,;]:  that  the  muscular  fibres  are  not 
thus  minutely  divided  :  that  a  single  fibre,  when  separated  from 

*  For  a  more  fall  and  interesting  account  of  these  microscopical  investiga- 
tions, see  Human  Physiology,  fourth  edition,  by  R.  Dunglison,  M.  D.,  Professor 
of  the  Institutes  of  Medicine  and  Medical  Jurisprudence  in  Jefferson  Medical 
College,  &c.  &c.  Phila.,  1845.— P. 

f  A  statement  of  these  descriptions,  with  reference  to  the  publications  in 
which  they  are  contained,  may  be  seen  in  the  Elementa  Physiologies  of  Haller, 
vol.  iv. 

$  Carlysle,  in  the  Croonian  Lecture,  London  Phylosophical  Transactions, 
1805,  Part  I. 


STRUCTURE   OF  MUSCULAR  FIBRES.  285 

the  adhering  extraneous  substances,  and  viewed  in  a  powerful 
microscope,  is  a  solid  cylinder,  formed  of  a  pulpy  substance, 
irregularly  granulated,  and  covered  by  a  portion  of  the  regular 
membrane. 

— The  opinions  of  Sir  A.  Carlysle,  are  not  at  the  present  time, 
deemed  of  much  weight  in  anatomy  ;  subsequent  researches 
having  shown  them  to  be  full  of  empty  and  reckless  speculation. 
Among  those  who  believed  the  muscular  fibre  to  be  hollow,  were 
Sink  and  Mascagni ;  the  latter  considered  it  as  formed  of  little 
cylinders,  the  walls  of  which  are  composed  of  absorbent  vessels 
and  filled  with  a  glutinous  substance.  More  recently,  Raspail 
(Chimie  Organique)  has  adopted  a  view  which  appears  a 
modification  of,  and  no  better  founded  than  that  of  Mascagni. 
He  considers  each  fibre  formed  of  a  bundle  of  cylinders,  the 
cylinders  made  up  of  elongated  vesicles,  attached  end  to  end, 
and  having  a  spiral  arrangement. — 

The  connexion  of  these  fibres  with  the  blood-vessels  and 
nerves,  is  an  important  circumstance  in  the  structure  of 
muscles. 

The  arteries  of  muscles  are  very  numerous  ;  and  they  ramify 
minutely.  They  are  accompanied  by  veins;  and  it  appears,  by 
the  successful  labors  of  Ruysch,  that  when  these  arteries  are 
fully  injected,  they  not  only  communicate  with  the  veins,  but 
also  pour  out  some  of  their  contents  in  a  dew-like  effusion  in  the 
muscle.* 

— With  the  exception  of  some  of  the  viscera,  as  the  lungs  and 
kidneys,  there  are  few  organs  that  receive  as  much  blood  as  the 
muscles. 

— The  arteries  that  supply  the  muscles,  enter  them  at  all  points. 
The  larger  trunks  more  generally  enter  at  the  middle  of  the 
muscle,  and  ramify  towards  each  extremity,  the  branches  being 
placed  between  the  larger  fasciculi  or  lacerti,  so  that  the  flow 
of  blood,  may  be  less  impeded  during  muscular  contraction  ; 
minute  branches  only  passing  into  the  structure  of  the  fasciculi. 


*  See  Ruysch's  description  of  the  96th  preparation  in  his  Thesaurus  Quartus  ; 
and  of  the  35th  preparation  in  Thesaurus  Decimus, 


286  VASCULARITY  OF  MUSCLES. 

The  veins  which  attend  the  arteries,  are  said  by  Bichat  to  have 
few  valves.  The  free  distribution  of  blood  to  the  muscles, 
appears  to  be  necessary  to  preserve  them  in  a  condition,  healthy 
and  capable  of  contraction.  When  the  supply  of  blood  is  cut 
off  by  a  ligature,  the  muscle  gradually  becomes  paralyzed,  and 
does  not  regain  its  power,  till  it  is  again  supplied  by  the  anasto- 
mosing branches. 

— The  color  of  the  muscle  does  not  seem  dependent  wholly  on 
the  blood,  but  in  part  at  least  on  their  own  peculiar  structure, 
as  seen  in  many  animals,  where  the  flesh  is  white  and  the  blood 
red  ;  and  in  the  muscles  of  organic  life  in  man,  many  of  which 
are  colorless,  though  more  vascular  than  those  of  animal  life. 
— The  absorbent  vessels  exist  no  doubt  in  all  the  muscles,  but 
they  are  traced  with  difficulty.  They  have  been  found  in  the 
muscles  of  the  tongue,  face  and  diaphragm.* — 

The  blood-vessels  must  terminate,  not  in  the  cavities  of  the 
muscular  fibres,  but  exterior  to  these  fibres  ;  otherwise  the 
dew-like  effusion,  would  not  be  apparent ;  and  it  is  probable, 
that  the  red  color,  which  is  so  general  in  muscles,  depends 
upon  a  portion  of  blood  effused  from  these  vessels,  and  not 
contained  in  them  ;  for  it  has  been  observed  by  Bichat,  that  in 
drowned  or  strangled  animals,  black  disoxygenated  blood 
occupied  all  the  vessels,  while  the  florid  color  of  the  muscles 
continued  unchanged  ;  which  could  not  have  been  the  case 
if  the  color  of  the  muscles  was  owing  to  the  blood  in  the 
vessels. 

That  the  color  of  the  red  muscles  is  owing  to  blood,  is 
rendered  certain  by  the  fact  that  this  color  may  be  completely 
washed  away  while  the  fibrous  structure  of  the  muscle  remains 
unchanged.  From  this  also  it  may  be  inferred  that  the  blood 
is  exterior  to  the  muscular  fibre,  and  to  the  vessels  likewise. 

It  is  said  by  Sabatier,  that  the  color  will  likewise  be 
completely  removed,  by  injecting  a.  large  quantity  of  water 
through  the  arteries  ;  this  does  not  invalidate  the  inferences 
drawn  from  the  other  facts  ;  for  the  water  effused  from  the 

*  Vide  Breschet,  Sur  le  Systeme  Absorbante.     Paris.  1836. 


THE  TENDONS.  287 

extreme  branches  of  the  arteries  must  necessarily  wash  away 
the  blood  which  was  previously  effused  from  the  same 
branches. 

The  water  with  which  muscles  have  been  washed,  appears  as 
if  some  blood  had  been  mixed  with  it ;  it  contains  albumen  and 
gelatine,  with  some  fibrine,  and  a  peculiar  extractive  substance, 
as  well  as  the  red  coloring  matter. 

The  substance  of  the  muscle,  when  thus  separated  from  the 
above  mentioned  matter  by  washing,  appears  to  be  of  the  same 
nature  with  the  fibrine  of  the  blood  :  and  after  boiling  some  time 
in  the  water,  it  seems,  like  that  substance,  to  consist  of  brown 
insoluble  fibres  which  are  brittle  when  dry. 

When  the  great  function  of  muscles  is  under  consideration, 
nerves  appear  of  more  importance  than  blood-vessels. 

The  nerves  appropriated  to  muscles  of  voluntary  motion  are 
more  numerous  than  those  appropriated  to  any  other  parts, 
except  the  organs  of  sense.  They  subdivide  into  very  fine 
fibrillae ;  and  it  is  the  opinion  of  one  of  the  latest  observers,  that 
these  fibrillae  become  soft  and  transparent,  and  finally  blended 
with  reticular  membrane  which  surrounds  the  muscular  fibres. 

It  ought  to  be  noted  that  muscles  are  indued  with  great  sensi- 
bility,- and  that  the  smallest  puncture  cannot  be  made  in  them 
without  exciting  pain. 

Of  the  Tendons. 

Thus  arranged,  the  fibres  of  muscles  are  most  generally  attach- 
ed to  tendons,  which  are  inserted  into  the  bones  these  muscles 
are  intended  to  move.  They  are  also,  in  some  cases,  inserted 
into  tendinous  membranes,  and  other  parts  necessary  to  be 
moved  ;  but  in  all  such  instances  these  parts  are  perfectly  pas- 
sive ;  and  the  motion  in  which  they  are  concerned  is  altogether 
produced  by  the  contraction  of  the  muscular  fibres. 

— The  tendons  appear  to  be  formed  of  a  continuation  of  the 
cellular  membrane  which  envelops  the  fibres  of  the  muscles. 
The  ultimate  construction  of  muscles  was  shown  in  page  283, 
to  consist  of  a  multitude  of  filaments  each  one  composed  of  a 
linear  series  of  the  muscular  molecules  ;  each  of  the  molecules 


288  THE  TENDONS. 

being  contained  in  a  series  of  cells  of  the  cellular  tissue,  all  of 
which  are  continuous  with  each  other.  The  muscular  matter  is 
found  in  general  only  in  the  middle  part  of  the  cellular  tissue ; 
the  latter  part  is  continued  on  at  each  extremity  of  the  muscle, 
where  it  is  compacted  into  a  solid  mass,  presents  a  ligamentous 
appearance,  and  constitutes  the  tendons,  or  cords  by  which  the 
muscles  are  attached  to  the»  periosteum  covering  the  bone. 
Hence  the  tendons  are  continuous  with,  and  must  obey  to  a 
certain  extent  the  contraction  of  every  muscular  fibre. 
— The  tendons  exist  under  a  great  variety  of  forms  :  most 
generally  round  or  cylindrical,  sometimes  flat,  radiated,  bifur- 
cated, etc.,  but  are  always  susceptible,  by  a  little  dissection,  of 
being  unfolded  into  a  membrane.  They  have  little  vascularity, 
no  sensation  in  a  healthy  state,  no  nerves  having  ever  been 
traced  into  them,  and  are  of  a  strength  surpassing  that  of  almost 
any  other  substance  of  equal  size.  They  have  a  great  affinity 
for  phosphate  of  lime,  especially  in  old  persons,  in  whom  it  is 
not  very  unusual  to  find  them  ossified  ;  and  very  frequently  at 
all  stages  of  life,  we  find  developed  in  their  substance  sesa- 
moid  bones. 

—The  muscles  are  often  from  inanition  or  want  of  use  much 
wasted  away,  the  red  muscular  matter  disappearing  from  the 
cells  in  which  its  particles  are  contained.  The  cells  however 
remaining,  if  the  system  regains  its  vigor,  or  the  muscles  are 
brought  into  use,  they  are  filled  anew  with  the  muscular  sub- 
stance or  myoline,  and  the  muscle  is  restored  to  its  former  size, 
and  its  contraction  takes  place  again  with  its  usual  force. 
- — From  this  mode  of  formation,  it  is  evident  that  there  must  be 
an  exact  relation  between  the  force  of  the  muscle,  and  the 
strength  of  its  tendons,  even  when  the  muscle  is  most  fully  de- 
veloped. The  size  and  power  of  the  muscle  is  much  dependent 
upon  its  use. 

w— The  muscles  of  the  legs  in  dancers,  of  the  arms  in  black- 
smiths, of  the  shoulders  and  back  in  porters,  all  obtain  an  in- 
crease of  bulk  from  use,  which  still  better  fits  them  for  the 
duties  they  have  to  perform.  This  is  strongly  exemplified  in 
birds  ;  the  breast  bone  and  muscles  attached  to  it  being  more 


PHENOMENA   Or  MUSCULAR  MOTION.  289 

strongly  developed  than  those  of  the  legs,  in  birds  which  are 
much  upon  the  wing  ;  the  reverse  taking  place  in  the  ostrich, 
cassowary  and  penguin,  which  employ  the  wings  only  as  akls  to 
the  feet. — 

Notwithstanding  the  great  attention  that  has  been  paid  to  this 
important  operation  of  muscular  fibres,  the  immediate  cause  is 
yet  unknown. 

Muscular  motion  takes  place  under  the  following  different 
circumstances  : — 

1st.  When  irritation  or  stimulus  is  applied  directly  to  the 
muscular  fibre. 

2d.  When  irritation  is  applied  to  a  nerve  connected  with  the 
muscles. 

3d.    When  it  is  induced  by  volition. 

There  are  several  causes  of  muscular  action  which  cannot  be 
arranged  under  either  of  these  heads,  although  it  is  probable  they 
are  not  essentially  different ;  such  as  the  motions  of  coughing 
and  sneezing,  of  yawning,  &c. 

The  immediate  irritation  of  a  muscle  is  effected  by  every 
mechanical  process,  which  punctures,  divides,  lacerates  or 
extends  its  fibres ;  by  acrid,  and,  perhaps,  other  chemical  and 
peculiar  qualities  of  the  substance  applied  to  the  muscles ;  by 
a  sudden  change  of  temperature;  and  by  electricity  and  gal- 
vanism. 

No  satisfactory  explanation  has  yet  been  made  of  the  man- 
ner in  which  muscular  contraction  is  excited,  either  by  the  above- 
mentioned  agents,  by  irritation  applied  to  a  nerve,  or  by  voli- 
tion. 

When  a  muscular  fibre  begins  to  contract,  there  is  often  the 
appearance  of  a  slight  tremor  in  it.  It  becomes  hard  and  rigid : 
its  length  diminishes,  and  its  diameter  increases.  If  a  muscle 
makes  an  effort  to  contract,  when  the  parts  to  which  its  extre- 
mities are  attached  are  prevented  from  moving  towards  each 
other,  so  that  contraction  cannot  take  place,  the  muscle  will 
become  hard  and  rigid  notwithstanding. 

— This  tremor  of  the  fibres,  is  called  fibrillary  agitation,  (agi- 
tation fibrillaire)  and  is  heard  when  a  stethoscope  is  applied 
25 


290  PHENOMENA  OF  MUSCULAR  MOTION. 

over  the  belly  of  a  muscle  during  its  contraction,  or  when  the 
end  of  the  finger  is  introduced  into  the  auditory  meatus.  During 
the  contraction  of  a  muscle  there  is  no  change  in  its  color,  nor  any 
increase  in  the  amount  of  blood  thrown  into  it  by  the  arteries  as 
was  once  supposed. 

Fig.  71.*  — With  the  aid  of  the  microscope  it  is  easy 
to  distinguish  the  manner  in  which  the 
contraction  of  a  muscle  is  effected.  Fig. 
70,  exhibits  a  magnified  view  of  the  mus- 
cular fibres  in  a  state  of  relaxation.  When 
they  contract  they  form  suddenly  a  num- 
ber of  zigzag  flexions,  or  angular  undula- 
tions, opposite  each  other,  as  seen  in  fig. 
'c  72,  page  291,  according  to  the  observation 
of  Edwards,!  Prevost,  and  Dumas.  By 
repeated  experiments,  these  gentlemen 
have  determined  that  the  flexures  of  each 
fibre  take  place  at  certain  determined  points,  and  nowhere  else. 
These  points  are  precisely  at  the  places  where  the  nerve  a,  the 
trunk  of  which  runs  parallel  with  the  muscular  fasciculi,  sends 
off  its  filaments  to  traverse  the  muscular  fibres,  at  the  spot  where 
the  angles  of  the  undulations  are  formed.  These  nervous  fila- 
ments after  having  continued  their  course  for  some  time,  are 
reflected  in  the  form  of  loops,  and  return  towards  the  brain,  so 
as  to  constitute  with  that  organ  a  continuous  circle. 
— During  the  contraction  of  the  muscle  its  extremities  ap- 
proach, for  though  the  absolute  length  of  the  fibre  remains  the 
same,  the  distance  between  its  extremities  is  diminished  by  the 
undulations.  The  will  transmitted  through  the  nerves  is  the 
usual  stimulus,  which  excites  the  voluntary  muscles  to  con- 
traction. Galvanic  electricity,  or  disease  of  nervous  centres 
will  produce  the  same  result ;  that  of  the  involuntary  muscles, 
usually  results  from  the  impression  made  upon  the  organs,  as 


*  a,  Nerve,  b  b,  Fasciculi  of  muscular  fibres  which  are  straight  and  parallel. 
e,  Nervous  filament  which  separates  from  the  nerve  a,  and  crosses  at  right 
angles,  and  at  regular  distances,  the  muscular  fasciculi. 

f  Elements  de  Zoologie,  etc.,  par  M.  H.  Edwards.    Paris,  1838. 


PHENOMENA  OF  MUSCULAR  MOTION.  291 

by  food  in  the  stomach,  blood  in   the  heart,  urine  in  the   blad- 
der, &c. — 

It  has  often  been  inquired  whether  the 
whole  bulk  of  a  muscle  is  diminished  or 
increased  by  its  contraction.  It  now  seems 
generally  agreed  that  the  bulk  is  not  increas- 
ed ;  and,  if  there  is  any  real  diminution  of 
the  fibre  itself,  it  is  very  small  indeed. 

The  irritability  of  the  muscular  fibre,  or 
its  power  of  contracting  upon  the  application 
of  stimulus,  exists  in  a  greater  degree  in 
some  muscular  parts  than  others.  It  is  sus- 
pended by  the  application  of  narcotic  sub- 
stances ;  and  it  remains,  in  many  cases,  a  short  time  after  the 
vital  functions  have  ceased. 

In  a  majority  of  cases  a  general  contraction  seems  to  take 
place  in  the  last  moments  of  life  ;  and  after  death  the  body  is 
stiff  in  consequence  of  it ;  all  the  movable  parts  being  fixed  in 
the  precise  situation  in  which  they  were  when  the  vital  motions 
ceased.  The  limbs  being  generally  in  a  bended  position  at  that 
time,  if  an  attempt  be  made  to  extend  them  it  will  be  very 
evident  that  the  contracted  state  of  the  muscles  impedes  this 
extension.  When  this  contraction  is  once  overcome,  the  limbs 
continue  perfectly  flexible,  and  the  muscles  are  ever  after 
relaxed ;  but  the  force  of  contraction  is  sometimes  so  great  that 
it  will  require  a  considerable  exertion  of  strength  to  overcome 
it.  This  condition  of  the  muscles,  after  death,  although  very 
common,  is  not  universal :  and  some  dead  subjects  are  perfectly 
relaxed  and  flexible  from  the  first  cessation  of  the  vital  func- 
tions. 

The  force  with  which  muscles  contract  exceeds  greatly  their 
inanimate  power  of  cohesion.  Thus,  a  muscle  deprived  of  life, 
would  be  completely  lacerated  by  a  weight  suspended  from  it, 
which  it  could  readily  raise  by  its  contraction  during  life.  This 
force  of  contraction  is  so  great,  that  the  tendo-achillis  and  the 

*  The  same  muscle  at  the  moment  of  contraction,  and  a  b  cf  indicates  the 
same,  as  in  Fig.  71. 


292  PHENOMENA  OF  MUSCULAR  MOTION. 

patella  have  been  repeatedly  broken  by  the  mere  power  of  the 
muscles,  inserted  into  them. 

The  rapidity  with  which  the  successive  contractions  of  the 
same  parts  take  place  is  extreme ;  and  as  a  striking  proof  of  it, 
the  motions  of  the  tongue,  in  rapid  speaking  or  reading,  are 
referred  to  by  physiologists. 

The  extent  or  degree  of  mustular  contraction,  is  in  some  cases, 
very  great.  In  proof  of  this  it  was  stated  by  the  second 
Monro,  that  crude  mercury,  which  passes  so  readily  through  the 
intestines,  could  not  be  carried  along  any  parts  of  them  whose 
position  happened  to  be  perpendicular,  (as  the  colon  on  the  right 
side  when  we  stand,)  unless  the  circular  fibres  of  the  intestine 
contract  behind  it  to  such  a  degree  as  to  close  completely  the 
cavity  of  that  tube. 

An  interesting  question  may  be  proposed  here, — Whether 
the  power  of  motion,  as  above  described,  is  exclusively  enjoyed 
by  muscular  fibres;  whether  these  fibres  must  be  supposed  to 
exist  in  all  those  parts  of  the  body  which  occasionally  perform 
contraction  ? 

It  has  often  been  inferred,  that  parts  were  muscular  because 
they  were  capable  of  contraction  ;  but  the  question  above  ought 
to  be  decided  affirmatively  before  such  inferences  can  be  pro- 
perly made. 

The  sac  of  the  taenia  hydatigena  appears  to  be  a  membrane 
of  a  peculiar  structure,  very  different  from  muscle ;  yet  it  is  as 
capable  of  contracting  as  if  it  were  perfectly  muscular.* 

The  membrane  of  the  urethra  does  not  appear  to  be  muscular 
in  its  structure ;  and  yet  it  has  been  seen  to  protrude  a  bougie, 
which  had  passed  near  to  the  neck  of  the  bladder,  in  a  way  that 
indicated  regular  successive  contraction,  throughout  its  whole 
extent. 

The  question  above  stated,  may,  therefore,  be  considered  as 
not  yet  decided  affirmatively. 

Muscular  fibres  are  situated  very  differently  in  different  parts. 
They  compose  almost  the  whole  substance  of  the  heart,  which 

*  See  the  Croonian  Lecture  by  Mr.  Home  ;  London  Philosophical  Transac- 
tions for  1795,  Part  I.  page  204. 


PHENOMENA  OF  MUSCULAR  MOTION.  293 

is  therefore  called  a  hollow  muscle.  They  also  form  one  of  the 
coats  of  the  stomach  and  intestines,  and  of  the  urinary  bladder. 

In  the  muscles  on  the  trunk  and  limbs,  their  arrangement  is 
very  various,  being  rectilinear,  penniform,  radiated,  &c. 

There  are  a  great  many  short  fibres,  with  an  oblique  direction, 
in  some  muscles  of  small  volume,  which  have  therefore  great 
power  and  little  motion,  as  in  the  semimembranosus. 

— Contraction,  though  the  only  power  that  muscles  appear 
to  exercise,  is  found  likewise  existing  to  some  extent,  in  other 
tissues  of  the  body,  where  some  effort  and  resistance  is  required 
in  the  performance  of  their  functions,  without  the  necessity 
of  that  perfect  antagonism  of  action  which  muscles  usually 
establish.  There  appears,  in  fact,  to  be  a  regular  gradation  in 
the  changes  of  the  condition  of  the  muscular  fibre.  The  mus- 
cles of  animal  life  in  man  are  the  most  fully  developed,  most 
highly  colored,  and  enjoy  to  the  fullest  extent,  the  powers  of 
contraction.  Their  only  vital  action  is  that  of  contraction, 
which  as  has  been  before  explained,  (see  page  291,)  causes 
their  ends  to  approach  each  other,  by  moving  one  or  the  other 
of  the  bones,  to  which  the  two  ends  of  the  muscles  are  attached. 
One  of  the  bones  is  usually  more  readily  moved  than  the  other, 
and  that  is  the  action  of  the  muscle  as  usually  set  down  in 
books.  But  the  student  will  do  well  to  impress  upon  his  mind, 
that  this  is  not  the  only  movement  which  the  muscle  can  effect, 
and  that  if  the  part  which  it  usually  moves,  becomes  from 
some  adventitious  cause  more  solidly  fixed  than  the  other, 
as  from  a  weight  attached  to  it,  or  the  opposing  action  of  other 
muscles,  the  contraction  of  the  muscle  will  produce  a  move- 
ment of  the  part,  at  which  its  other  extremity  is  inserted.  In 
this  way  the  action  of  muscles  is  beautifully  varied,  and  very 
complicated  and  useful  movements  are  produced  in  the  body, 
by  what  seems  a  very  simple  arrangement  of  the  muscles. 
Thus  the  action  of  the  great  pectoral  and  latissimus  dorsi  mus- 
cles is  usually  to  pull  down  the  arms  when  they  have  been 
elevated  by  other  muscles.  But  if  the  arms  are  thrown 
upwards,  and  the  hands  grasp  some  place  above,  as  the  limbs 
25* 


294  ANTAGONISM  OF  MUSCLES. 

of  a  tree,  they  then  raise  the  body  upwards  towards  the  arms, 
and  thus  become  the  muscles  used  in  climbing. 
— In  violent  dyspnoea,  arising  from  spasmodic  croup,  asthma,  or 
other  causes,  the  arms  are  frequently  drawn  upwards  so  firmly 
by  the  muscles  at  the  top  of  the  shoulders,  that  the  pectoralis 
major  and  latissimus  dorsi  cannot  pull  them  down.  When  they 
contract,  therefore,  their  extremities  are  made  to  approach 
by  raising  the  ribs  to  which  they  are  in  part  attached,  and  thus 
they  become  muscles  of  forced  inspiration. 
— The  muscles  of  animal  life  are  arranged,  so  that  each  one  has 
its  antagonist,  or  opposing  muscle.  Thus,  there  are  flexors  to 
bend  the  limbs,  and  extensors  to  straighten  them,  supinators  and 
pronators,  elevators  and  depressors.  The  muscles,  which  are 
very  numerous,  and  like  the  bones,  are  said  to  be  variously 
estimated,  from  368  by  Chaussier,  to  400  or  more  by  other 
writers,  and  producing  by  their  single  action  a  great  variety  of 
movements,  are  yet  combined  together  in  pairs  or  much  larger 
numbers,  so  as  to  extend  beyond  computation  the  variety  of 
movements  they  are  capable  of  producing.  Thus  the  two  mus- 
cles already  named,  one  of  which,  when  acting  separately,  draws 
the  arm  usually  downwards  and  forwards,  the  other  downwards 
and  backwards,  when  combined  together  draw  it  down  in  the 
diagonal  or  middle  line. 

— The  antagonism  of  the  muscles  is  dependent  upon  their  alter- 
nate contraction  :  the  shortened  or  contracted  muscle,  is  re- 
stored to  its  former  length  chiefly  by  the  contraction  of  its  an- 
tagonist, but  partly  also  by  the  resiliency  of  the  cellular  tissue 
in  its  composition.  They  are  also  capable  of  acting  to  a  certain 
extent  in  unison,  and  thus  give  firmness  and  steadiness  to  the 
limbs  or  other  parts,  and  hold  them  in  a  fixed  direction,  as 
occurs  habitually  in  walking  or  standing,  or  pointing  with  the 
arm. 

— The  antagonizing  muscles  do  not  appear  to  be  equally 
balanced  in  regard  to  power;  thus  the  most  usual  attitudes,  in 
sleep,  palsy  or  tetanus,  where  the  muscles  are  uninfluenced  by 
the  will,  is  the  extended  position  for  the  back,  flexion  to  the 
arm  in  general,  pronation  to  the  fore  arm,  flexion  to  the  lower 


MODE  OF    INSERTION.  295 

extremities  and  adduction  to  the  foot.  This  is  not  dependent 
upon  a  difference  in  length,  as  was  supposed  by  Borelli,  but, 
according  to  Beclard,  chiefly  upon  a  difference  in  size,  ^nd  the 
relative  advantages  of  insertion  upon  the  bones. 
— Muscles  have  their  tendons  attached  to  the  bones,  in  a  man- 
ner to  give  them  the  least  mechanical  power,  but  to  effect  the 
greatest  rapidity  of  motion  ;  for,  as  has  been  observed  by 
Archdeacon  Paley,  it  is  of  far  greater  importance  to  man,  to  be 
able  to  carry  his  arm  quickly  to  his  head,  than  to  raise  several 
hundred  weight  more  than  he  is  now  able  to  do :  the  two 
qualities  could  not  well  exist  together.  All  that  could  be  done 
to  increase  the  power,  without  impairing  the  symmetry  of  the 
body,  or  diminishing  the  celerity  of  its  movements,  has  been 
accomplished  in  endowing  the  muscles,  with  an  extraordinary 
force  of  contraction,  at  least  ten  fold  as  great  as  the  student 
would  at  first  suppose  it.  The  muscles  are  nearly  all  levers  of 
the  third  order. 

— The  force  with  which  a  muscle  contracts,  depends  upon  its 
volume  and  the  energy  of  the  will,  as  well  as  some  other  circum- 
stances. But  the  effect  produced  by  the  contraction  will 
depend  in  a  great  measure  upon  the  manner  in  which  it  is 
inserted  upon  the  bone  on  which  it  acts. 

— Thus,     all      things      being     the 
same,  the    effect    of    the    contrac- 
tion will  be  the  greater,  in   propor- 
tion as  the  muscle  is  less  obliquely 
*  connected    with    the    bone.      Thus 
if    the   muscle    m,    figure   73,    the 
t  force  of  which   we  suppose  equal 

to   10,  is   fixed    perpendicularly   to 

the  bone  Z,  the  extremity  of  which  a,  is  movable  upon  the 
fulcrum  point  r,  it  will  have  to  overcome  only  the  weight  of 
the  bone,  and  will  carry  it  from  the  position  a  6,  into  the  direc- 
tion of  the  line  a  c.  But  if  this  muscle  acted  obliquely  upon 
the  bone  in  the  direction  of  the  line  n  b,  it  would  then  tend  to 
carry  it  in  the  direction  of  the  line  b  n,  and  consequently  to 
force  it  against  the  fixed  articular  surface  r.  This  latter  being 


296  FORCE  OF  MUSCULAR  CONTRACTION. 

a  fixed  surface,  the  bone  can  only  turn  upon  the  point  r,  as 
upon  a  pivot,  and  the  contraction  of  the  muscle  71,  having  the 
same  force  as  the  muscle  m,  would  only  be  able  to  carry  the 
bone  in  the  direction  a  d,  and  would  require  a  force  equal  to 
40,  or  four  times  that  of  m,  to  raise  it  in  the  direction  of  the 
line  a  c. 

—In  the  animal  economy  the  muscles  are  inserted  most  usually, 
very  oblic[uely,  and  consequently  in  a  manner  little  favorable 
to  the  intensity  of  the  result  of  their  contraction.  There  is 
nevertheless  a  very  happy  contrivance,  which  tends  to  diminish 
the  obliquity  of  their  insertions,  without  marring  the  usefulness 
or  symmetry  of  the  limbs.  It  is  the  articular  swellings  at  the 
extremities  of  the  bones,  which  contribute  also  to  the  stability  of 
the  joints,  the  advantage  of  which  is  seen  in  fig.  74. 
— The  tendon  i  of  the  muscle  m,  Fig.  74,  is  inserted  as  is  the  case 
in  general  immediately  below  the  articula- 
tion, upon  the  mobile  bone  o,  in  a  direc- 
tion more  approaching  the  perpendicular, 
thus  making  the  head  of  the  bone  a  sort  'm""" 
of  pulley  over  which  it  acts,  by  which  the 
effect  of  the  contraction  is  considerably 
increased. 

— A  more  striking  instance  is  met  with  in  the  deltoid  muscle. 
Baron  Haller,  has  made  an  interesting  calculation  of  the  abso- 
lute force  required  to  be  exerted  by  the  deltoid  muscle,  in  order 
to  raise  a  weight  of  60  pounds  at  the  elbow,  reckoning  the  weight 
of  the  arm  at  five  pounds  of  this.  Its  insertion  is  at  an  angle  of  10 
degrees  upon  the  humerus,  and  at  about  one-third  of  the  distance 
between  the  shoulder  and  elbow.  The  force  requisite  to  raise  a 
weight  is  exactly  in  the  proportion  of  the  distance,  which  the 
weight  from  the  fulcrum  bears  to  that  of  the  power  from  the 
fulcrum.  Thus,  from  the  disadvantage  of  insertion,  the  force 
requisite  to  be  exercised  there  is  three  times  as  great  as  it  would 
be  if  inserted  at  the  elbow ;  therefore  the  actual  weight  lifted, 
as  far  as  the  muscle  is  concerned,  is  equal  to  180  pounds. 
— But  this  is  not  all.  The  insertion  of  the  muscle  at  an  angle 
of  10  instead  of  90  degrees,  takes  off  the  purchase  in  the 


MUSCLES     OF    ORGANIC    LIFE.  297 

proportion,  as  mathematicians  have  calculated,  which  173  bears 
to  1000.  The  augmented  weight,  or  what  is  the  same  thing, 
the  increase  of  power  necessary  to  raise  it,  amounts,  therefore, 
to  no  less  than  1058,  instead  of  the  original  60  pounds.  There 
is  yet  another  source  of  loss  of  effect  in  its  contraction,  which 
requires  great  additional  power  in  the  muscle  to  counteract  it. 
The  tendon  of  the  muscle  is  never  directly  continuous  with  the 
muscular  fibres,  and  the  loss  of  power  is  exactly  in  proportion 
to  the  obliquity  of  their  junction.  The  manner  of  this  loss  is 
evinced,  when  we  attempt  to  draw  a  body  to  us,  at  one  time 
with  a  crooked,  and  at  another,  with  a  straight  bar  or  stick. 
From  this  cause  there  would  be  a  further  loss  of  power  of  228 
pounds,  which  would  augment  the  muscular  energy,  required  to 
raise  the  60  pounds,  up  to  1284,  according  to  this  physiologist. 
— In  the  muscles  of  organic  life,  destined  to  act  without  the  aid 
of  the  will,  the  system  of  antagonism,  is  much  less  perfectly 
developed.  These  muscles  are  hollow,  and  their  fibres  are 
arranged  generally  into  layers,  which  cross  each  other  at  right 
angles,  and  contribute,  to  a  certain  extent,  to  produce  this  effect. 
The  alternate  contractions,  of  the  auricles  and  ventricles  of  the 
heart,  and  of  the  uterus,  though  these  organs  have,  properly 
speaking,  no  antagonist  muscles,  belong  to  this  class.  In  some 
of  the  hollow  organs,  as  the  bladder,  the  contracted  muscular 
fibres  are  expanded  or  antagonized,  only  by  the  matters  which 
collect  in  their  cavities. 

— The  muscles  of  organic  life,  with  the  exception  of  the  heart, 
are  of  a  pale  or  greyish  white  color.  Some  of  them  are  so 
thin,  and  of  so  pale  a  color,  that  it  is  impossible  to  draw  the 
line  of  distinction  between  them  and  cellular  or  aponeurotic 
tissue. 

— There  is  a  regular  gradation  between  muscular  and  desmoid 
cellular  tissue,  now  called  contractile  fibre  or  contractile  tissue, 
and  an  occasional  substitution  of  the  one  for  the  other,  in  parts 
that  require  elastic  resistance,  or  firm  support,  that  has  been 
overlooked  by  many  anatomists.  The  yellow  elastic  ligarnen- 
tous  tissue,  appears  to  be  one  medium  between  the  muscular 
and  ligamentous  tissue.  Comparative  anatomy  shows  us  that 


298  CONTRACTILE    TISSUE. 

parts  formed  in  one  animal  of  the  elastic  yellow  tissue,  are  in 
others  composed  of  muscular  fibres.  Thus,  the  suspensory 
ligaments  of  the  sheath  of  the  penis,  are  ligamentous  in  the 
horse,  and  muscular  in  the  mule  and  bull.  The  middle  coat  of 
the  arteries,  which  is  composed  of  the  elastic  yellow  tissue  in 
man,  is  muscular  in  certain  parts  of  the  arterial  system  of  the 
elephant. 

— The  kindred  nature  of  these  two  tissues,  is  likewise  strongly 
manifested  by  chemical  analysis.  The  yellow  elastic  tissue 
consists  chemically  of  albumen,  osmazome  and  fibrine.*  The 
thick  yellow  elastic  ligament  which  supports  the  weight  of  the 
abdominal  viscera  in  the  horse,  and  others  of  the  solipediae, 
consists,  in  man,  only  of  the  fascia  superficialis  abdominis,  and 
forms,  as  a  late  writer  is  disposed  to  think,  the  abdominal  pouch, 
(poche  musculaire,)  of  the  didelphic  animals,  such  as  the 
opossum  and  kangaroo. 

— The  parietes  of  the  urethra,  which,  in  man,  is  strongly  elastic, 
in  the  horse  and  many  other  animals  is  endowed  with  a  strong 
coat  of  palish  muscular  fibres.  On  close  examination  it  will 
be  found  in  man,  that  the  reddish  fibres  of  the  contractile  tissue 
which  constitute  the  dartos  muscle,  are  also  extended  so  as  to 
cover  the  corpus  cavernosum  penis  and  the  urethra  ;  over  this 
latter  organ  it  is  not  improbable  that  they  sometimes  become  the 
seat  of  stricture.  They  run  more  or  less  parallel,  and  near  to 
one  another,  over  the  scrotum,  where  they  are  interwoven  with 
transverse  fibres  and  bundles  of  cellular  substance — or  they 
form  plexuses,  as  on  the  penis,  which  resemble  the  terminal 
plexuses,  of  nerves,  with  this  difference,  that  the  individual 
fibres  interlace  and  amalgamate. 

— This  same  reddish  contractile  fibre  is  found  by  the  microscope  to 
be  interwoven  in  various  places  with  the  tissue  of  the  skin,  and 
that  peculiar  corrugation  of  the  skin  known  under  the  name  of 
goose  flesh,  is  supposed  to  be  produced  by  their  agency.  They 
act  with  such  force  upon  the  scrotum,  as  occasionally  to  make 
it  hard  as  a  ball,  shrink  it  greatly  in  size,  and  force  the  testicles 

*  Consid.  sur  les  aponeuroses  abdom.  servant  d'introduction  a  1'histoire  des 
Hernies,  dans  les  Monodactyles,  par  Girard,  fils. 


CHEMICAL    COMPOSITION.  299 

up  towards  the  inguinal  rings.  This  contractile  tissue  enters 
as  an  element,  into  the  constitution  of  the  penis  and  clitoris, 
and  probably  also  into  that  of  the  blood  vessels,  and  the'excre- 
tory  ducts  of  the  glands.  When  viewed  under  the  microscope, 
the  contractile  fibre  is  found  different  from  the  round  fibres  of 
the  common  fibrous  tissue ;  they  are  larger,  redder,  and  possess 
a  peculiar  kind  of  transparency.  The  muscular  fibres  on  the 
inner  face  of  the  prostrate  glands,  and  the  muscles  of  Wilson 
on  the  membranous  part  of  the  urethrae  seem  to  be  allied  to 
this  class  of  tissue.  This  opinion  seems  borne  out  by  the  de- 
velopment of  the  muscles  in  the  foetus,  as  previously  quoted 
from  Isenflam. 

— Muscles  are  composed  chemically,  according  to  Berzelius, 
principally  of  fibrine  ;  but  they  contain  also  albumen,  gelatine, 
osmazome,  phosphates  of  soda,  ammonia  and  lime,  carbonate 
of  lime,  and  some  free  lactic  acid.  If  the  analysis  is  pushed 
farther— to  the  destruction  of  the  flesh,  there  is  developed  a  great 
quantity  of  nitrogen,  hydrogen,  oxygen  and  carbon,  some  iron, 
phosphorus,  soda  and  lime. 


300  INDIVIDUAL    MUSCLES. 


CHAPTER  VIII. 

OF  THE  INDIVIDUAL  MUSCLES. 

Muscles  of  the  Teguments  of  the  Cranium. 

THE  skin  that  covers  the  cranium  is  moved  by  a  single  broad 
digastric  muscle,  and  one  small  pair. 

1 .   Occipito-Frontalis, 

.Arises  fleshy  from  the  transverse  protuberant  ridge  near  the 
middle  of  the  os  occipitis  laterally,  where  it  joins  with  the  tem- 
poral bone ;  and  tendinous  from  the  rest  of  that  ridge  back- 
wards, opposite  to  the  lateral  sinus ;  it  rises  after  the  same 
manner  on  the  other  side.  From  thence  it  comes  straight 
forwards,  by  a  broad  thin  tendon,  which  covers  the  upper  part 
of  the  cranium  at  each  side,  as  low  down  as  the  attollens  auris, 
to  which  it  is  connected,  as  also  to  the  zygoma,  and  covers  a  part 
of  the  aponeurosis  of  the  temporal  muscle ;  at  the  upper  part  of 
the  forehead  it  becomes  fleshy,  and  descends  with  straight  fibres. 

Inserted  into  the  orbicularis  palpebrarum  of  each  side,  and 
into  the  skin  of  the  eyebrows,  sending  down  a  fleshy  slip  be- 
tween them,  as  far  as  the  compressor  naris  and  levator  labii 
superioris  alaeque  nasi. 

Use.  Pulls  the  skin  of  the  head  backwards  ;  raises  the  eye- 
brows upwards  ;  and,  at  the  same  time,  it  draws  up  and  wrin- 
kles the  skin  of  the  forehead. 

2.   Corrugator  Supercilii, 

Arises  fleshy  from  the  internal  angular  process  of  the  os 
frontis,  above  the  joining  of  the  os  nasi  and  nasal  process  of 
the  superior  maxillary  bone ;  from  thence  it  runs  outwards,  and 
a  little  upwards. 

Inserted  into  the  inner  and  inferior  fleshy  part  of  the  occipito- 
frontalis  muscle,  where  it  joins  with  the  orbicularis  palpebrarum, 


MUSCLES  OF  THE  EAR. 


301 


75.* 


and  extends  outwards   as  far  as  the  middle  of  the  superciliary 
ridge. 

Use.  To  draw  the  eyebrow  of  that  side  towards  trie  other, 
and  make  it  project  over  the  inner  canthus  of  the  eye.  When 
both  act,  they  pull  down  the  skin  of  the  forehead,  and  make  it 
wrinkle  particularly  between  the  eyebrows. 

Muscles  of  the  Ear. 
1.  Attollens  Auris, 

Arises,   thin,   broad,   and  tendinous,  from  the   tendon  of  the 

occipito-frontalis,  from 
which  it  is  almost  in- 
separable, where  it  co- 
vers the  aponeurosis  of 
the  temporal  muscle. 

Inserted  into  the  up- 
per part  of  the  ear,  op- 
posite to  the  antihelix. 

Use.  To  draw  the  ear 
upwards,  and  make  the 
parts,  into  which  it  is 
inserted,  tense. 

2.   Anterior  Auris , 

Arises,  thin  and  mem- 
branous, near  the  pos- 
terior part  of  the  zygo- 
ma. 

Inserted   into  a   small 
eminence  on  the  back  of 
the  helix,  opposite  to  the 
*!  yW  •'  "v  concha. 

Use.     To  draw  this  eminence  a  little  forwards  and  upwards. 


*  g,  Occipito-frontalis.     m,  Nasal  slip  of  do. 
Levator  labii  superioris  alseque  nasi.    5,  Masseter. 


n,  Compressor  naris.     k, 
q,  Attollens  auris.    r,  Re- 


trahentes  auris,  usually  two  in  number,  p,  Platysma  myoides.  5,  Sterno- 
cleido-mastoid.  u,  Trapezius.  v,  Splenius  capitis.  i,  Splenius  colli.  TV,  Del- 
toid. The  rest  of  the  muscles  known  by  references  to  the  cuts  No.  76,  77,  78. 

26 


30*2  MUSCLES  OF  THE  EYELIDS. 

3.  Retrahentes  Auris, 

Arise,  sometimes  by  three,  but  always  by  two  distinct  small 
muscles,  from  the  external  and  posterior  part  of  the  root  of  the 
mastoid  process,  immediately  above  the  insertion  of  the  sterno- 
cleido-mastoid  muscle. 

Inserted  into  that  part  of  the^back  of  the  ear  which  is  oppo- 
site to  the  septum  that  divides  the  scapha  and  concha. 

Use.     To  draw  the  ear  back,  and  stretch  the  concha. 

Muscles  of  the  Eyelids. 

The  palpebrae  or  eyelids,  have  one  muscle  common  to  both, 
and  the  upper  eyelid  one  proper  to  itself. 

1.    Orbicularis  Palpebrarum, 

Arises,  by  a  number  of  fleshy  fibres,  from  the  outer  edge  of 
the  orbitar  process  of  the  superior  maxillary  bone,  and  from  a 
tendon  near  the  inner  angle  of  the  eye ;  these  run  a  little  down- 
wards, then  outwards,  over  the  upper  part  of  the  cheek,  below 
the  orbit  covering  the  under  eyelid,  and  surround  the  external 
angle,  being  loosely  connected  only  to  the  skin  and  fat ;  run 
over  the  superciliary  ridge  of  the  os  frontis,  towards  the  inner 
canthus,  where  they  intermix  with  those  of  the  occipito-fron- 
talis  and  corrugator  supercilii ;  then  covering  the  upper  eyelid, 
they  descend  to  the  inner  angle  opposke  to  the  inferior  origin 
of  this  muscle,  firmly  adhering  to  the  internal  angular  process 
of  the  os  frontis,  and  to  the  short  round  tendon  which  serves  to 
fix  the  palpebrae  and  muscular  fibres  arising  from  it. 

Inserted,  by  the  short  round  tendon,  into  the  nasal  prdcess 
of  the  superior  maxillary  bone,  covering  the  anterior  and  upper 
part  of  the  lachrymal  sac  ;  which  tendon  can  be  easily  felt  at 
the  inner  canthus  of  the  eye. 

Use.  To  shut  the  eye,  by  drawing 'both  lids  close  together, 
the  fibres  contracting  from  the  outer  angle  towards  the  inner, 
press  the  eyeball,  squeeze  the  lachrymal  gland,  and  convey  the 
tears  towards  the  puncta  lachrymalia. 

— When    the  muscle   is   in    strong   action,  its   upper   fibres 


MUSCLES    OF    THE    EYEBALL.  303 

cause  the  skin  of  the  forehead  to  descend,  the  lower  ones  elevate 
the  integuments  of  the  cheek.  Like  the  other  sphincters,  this 
is  a  mixed  muscle.  The  fibres  which  are  supposed  te»  be  the 
proper  voluntary  portion,  are  those  which  correspond  to  the 
margin  of  the  orbit,  and  are  of  a  red  color.  The  involuntary 
fibres,  form  the  thin  portion  which  covers  the  lids,  (musculus 
ciliaris  of  Albinus,)  and  are  of  a  pale  color,  like  the  muscles 
of  organic  life.  They  contract  involuntarily  while  we  are  awake, 
in  the  action  of  winking,  and  during  sleep  in  maintaining  the 
lids  closed. — 

The  ciliaris  of  some  authors  is  only  a  part  of  this  muscle 
covering  the  cartilages  of  the  eyelids,  called  cilia  or  tarsi. 

There  is  often  a  small  fleshy  strip,  which  runs  down  from 
the  outer  and  inferior  part  of  this  muscle  above  the  zygomati- 
cus  minor,  and  joints  with  the  levator  labii  superioris  alaeque 
nasi. 

2.    Levator  Palpebrce  Superioris, 

Arises  from  the  upper  part  of  the  foramen  opticum  of  the 
sphenoid  bone,  through  which  the  optic  nerve  passes,  above  the 
levator  oculi,  near  the  trochlearis  muscle. 

Inserted,  by  a  broad  thin  tendon,  into  the  cartilage  that  sup- 
ports the  upper  eyelid,  named  tarsus. 

Use.  To  open  the  eye,  by  drawing  the  eyelid  upwards ; 
which  it  does  completely,  by  being  fixed  to  the  tarsus,  pulling 
it  below  the  eyebrow,  and  within  the  orbit.*' 

Muscles  of  the  Eyeball 

The  muscles  which  move  the  globe  of  the  eye  are  six,  viz  : 
four  straight,  and  two  oblique. 

The  four  straight  muscles  very  much  resemble  each  other  :  all 

Arising  by  a  narrow  beginning,  a  little  tendinous  and  fleshy, 

from  the  bottom  of  the  orbit  around   the  foramen  opticum  of 

the  sphenoid  bone,  where  the  optic  nerve  enters,  so  that  they 

*  There  is  no  antagonist  muscles  provided  especially  to  depress  the  lower  lid. 
Its  depression  is  effected,  according  to  the  suggestion  of  Sir  C.  Bell,  by  the  pro- 
trusion of  the  eyeball. — p. 


MUSCLES   OF  THE  EYE. 

may  be  taken  out  adhering  to  this  nerve  ;  and  all  having  strong 
fleshy  bellies. 

Inserted  at  the  forepart  of  the  globe  of  the  eye  into  the  ante- 
rior part  of  the  tunica  sclerotica,  and  under  the  tunica  adnata, 
at  opposite  sides,  which  indicates  both  their  names  and  Use ;  so 
that  they  scarcely  require  any  farther  description  than  to  name 
them  singly.  The  union  of  thai  tendinous  insertions  forms  the 
tunica  albuginea. 

1.    Levator  Oculi,  (Rectus  Superior,) 
Arises  from   the   upper  part  of  the  foramen  opticum  of  the 

sphenoid  bone,  below  the  levator  palpebra?  superioris,  and  runs 

forwards  to  be 

Inserted  into  the  superior  and  forepart  of  the  tunica  sclerotica, 

by  a  broad  thin  tendon. 

Use.    To  raise  up  the  globe  of  the'  eye. 

2.  Depressor  Oculi,  (Rectus  Inferior,) 
Arises  from  the  inferior  part  of  the  foramen  opticum. 
Inserted  opposite  to  the  former. 

Use.    To  pull  the  globe  of  the  eye  down. 

3.  Adductor  Oculi,  (Rectus  Internus,) 

Fig.  76.*  Arises,  as    the  former,   be- 

tween the  obliquus  superior 
and  depressor,  being  from  its 
situation,  the  shortest. 

Inserted  opposite  to  the  in- 
ner angle. 

Use.    To  turn   the  eye  to- 
wards the  nose. 

*  The  muscles  of  the  eyeball ;  the  view  is  taken  from  the  outer  side  of  the 
right  orbit.  1,  A  small  fragment  of  the  sphenoid  bone  around  the  entrance  of 
the  optic  nerve  into  the  orbit.  2.  The  optic  nerve.  3.  The  globe  of  the  eye. 
4.  The  levator  palpebrse  muscle.  5.  The  superior  oblique  muscle.  6.  Its  car- 
tilaginous pulley.  7.  Its  reflected  tendon.  8.  The  inferior  oblique  muscle,  the 
small  square  knob  at  its  commencement  is  a  piece  of  its  bony  origin  broken  off. 
9.  The  superior  rectus.  10.  The  internal  rectus  almost  concealed  by  the  optic 
nerve.  11.  Part  of  the  external  rectus,  showing  its  two  heads  of  origin. 
32.  The  extremity  of  the  external  rectus  at  its  insertion  ;  the  intermediate  por- 
tion of  the  muscle  having  been  removed.  13.  The  inferior  rectus.  14.  The 
tunica  albuginea,  formed  by  the  expansion  of  the  tendons  of  the  four  recti. 


MUSCLES  OF  THE  EYE.  305 

4.   Abductor  Oculi,  (Rectus  Externus,) 

Arises  from  the  bony  partition  between  the  foramen  opticum 
and  foramen  lacerum,  being  the  longest  from  its  situation ; 
and  is 

Inserted  into  the  globe  opposite  to  the  outer  canthus. 

Use.    To  move  the  globe  outwards. 

The  oblique  muscles  are  two  :  « 

Obliquus  Superior,  seu  Trochlearis, 

Arises,  like  the  straight  muscles,  from  the  edge  of  the  fora- 
men opticum  at  the  bottom  of  the  orbit,  between  the  levator 
and  abductor  oculi ;  from  thence,  runs  straight  along  the  pars 
plana  of  the  ethmoid  bone  to  the  upper  part  of  the  orbit,  where 
a  cartilaginous  trochlea  is  fixed  to  the  inside  of  the  internal 
angular  process  of  the  os  frontis,  through  which  its  tendon 
passes,  and  runs  a  little  downwards  and  outwards,  enclosed  in  a 
loose  membranous  sheath. 

Inserted  by  a  broad  thin  tendon,  into  the  tunica  sclerotica, 
about  half  way  between  the  insertion  of  the  attollens  oculi  and 
optic  nerve. 

Use.  To  roll  the  globe  of  the  eye,  and  turn  the  pupil  down- 
wards and  outwards,  so  that  the  upper  side  of  the  globe  is 
turned  inwards,  and  the  inferior  part  to  the  outside  of  the 
orbit,  and  the  whole  globe  drawn  forwards  towards  the  inner 
canthus. 

2.   Obliquus  Inferior, 

Arises,  by  a  narrow  beginning,  from  the  outer  edge  of  the 
orbitar  process  of  the  superior  maxillary  bone,  near  its  juncture 
with  the  os  unguis ;  and  running  obliquely  outwards,  is 

Inserted  into  the  sclerotica,  in  the  space  between  the  abductor 
and  optic  nerve,  by  a  broad  and  thin  tendon. 

Use.   To  draw  the  globe  of  the  eye   forwards,  inwards,  and 

downwards  ;    and,  contrary  to  the  superior,  to  turn   the  pupil 

upwards  towards  the   inner  extremity  of  the  eyebrow  ;  at  the 

same  time,  that  the  external  part  of  the  globe  is  turned  towards 

26* 


306  MUSCLES  OF    THE  NOSE. 

the   inferior   side,   and    the   internal    rolls    towards  the   upper 
part. 

The  Muscle  of  the  Nose. 

There  is  only  one  muscle  on  each  side  that  can  be  called 
proper  to  the  nose,  though  it  is  affected  by  several  muscles  of 
the  face. 

Compressor  Naris,  (Triangularis  seu  Transversalis  .Mm*,) 

Arises,  by  a  narrow  beginning,  from  the  root  of  the  ala  nasi 
externally,  where  part  of  the  levator  labii  superioris  alaeque 
nasi  is  connected  to  it ;  it  spreads  into  a  number  of  thin  separate 
fibres,  which  run  up  along  the  cartilage  in  an  oblique  manner 
towards  the  dorsum  of  the  nose,  where  it  joins  with  its  fellow, 
and  is 

Inserted  slightly  into  the  anterior  extremity  of  the  os  nasi  and 
nasal  process  of  the  superior  maxillary  bone,  where  it  meets 
with  some  of  the  fibres  descending  from  the  occipito-frontalis 
muscle.* 

Use.  To  compress  the  ala  towards  the  septum  nasi,  particu- 
larly when  we  want  to  smell  acutely  ;  but,  if  the  fibres  of  the 
frontal  muscle,  which  adhere  to  it,  act,  the  upper  part  of  this 
thin  muscle  assists  to  pull  the  ala  outwards.  It  also  corrugates 
the  skin  of  the  nose,  and  assists  in  expressing  certain  passions. 
— It  has  been  called  by  Columbus  dilatans  nasi,  from  a  belief, 
in  which,  Bourgery  coincides,  that  when  it  acts  with  its  extrem- 
ity upon  the  nose  as  the  fixed  point,  it  dilates  the  nostril. 
When  the  other  extremity  of  the  muscle  is  the  fixed  point,  it 
compresses  it. — 

Muscles  of  the  Mouth  and  Lips. 

The  mouth  has  nine  pair  of  muscles,  which  are  inserted  into 
the  lips,  and  a  common  one  formed  by  the  termination  of  these ; 

*  The  nasal  slip  of  fibres  descending  from  the  occipito-frontalis,  is  some- 
times spoken  of  as  a  distinct  muscle,  under  the  name  of  Pyramidalis  nasi. 


MUSCLES  OF  THE  MOUTH  AND  LIPS. 


307 


viz.  three  above,  three  below,  three  outwards,  and  the  common 
muscle  surrounds  the  mouth. 
The  three  above  are, 

1.   Levator  Anguli  Oris, 


Arises,  thin  and  fleshy, 
from  the  hollow  of  the 
superior  maxillary  bone, 
between  the  root  of  the 
socket  of  the  first  dens 
molaris  and  the  foramen 
infra  orbitarium. 

Inserted  into  the  an- 
gle of  the  mouth  and 
under  lip,  where  it  joins 
with  its  antagonist. 

Use.  To  draw  the  cor- 
ner of  the  mouth  up- 
wards, and  make  that 
part  of  the  cheek  oppo- 
site to  the  chin  promi- 
nent, as  in  smiling. 


Fig.  77  * 


2.   Levator  Labii  Superioris  Alaque  Nasi, 

Arises  by  two  distinct  origins :  the  first  broad  and  fleshy, 
from  the  external  part  of  the  orbitar  process  of  the  superior 
maxillary  bone  which  forms  the  lower  part  of  the  orbit,  imme- 

*  g,  Occipito-frontalis.  I,  Levator  labii  superioris  alaeque  nasi.  I,  Levator 
anguli  oris.  n,  Compressor  naris.  o,  Orbicularis  palpebrarum ;  the  external 
palpebral  ligament,  seen  on  the  right  side,  extending  to  the  ear.  3  3,  Zygoma- 
ticus  major,  and  minor.  4,  Orbicularis  oris,  with  the  slip  to  the  lower  part  of 
the  septum  of  the  nose,  called  by  Albinus,  nasalis  labii  superioris.  5,  Masseter. 
t,  Depressor  anguli  oris.  s  s,  Sternal  and  clavicular  portions  of  the  sterno- 
cleido-mastoid.  u,  Trapezius  seen  at  its  upper  part.  6,  Sterno-hyoid.  7, 
Sterno-thyroid.  8,  Omo-hyoid.  9,  Scalenus  anticus.  10,  Scalenus  medius. 


308  MUSCLES  OF    THE  FACE. 

diately  above  the  foramen  infra-orbitarium  ;  the  second  portion 
arises  from  the  nasal  process  of  the  superior  maxillary  bone, 
where  it  joins  the  os  frontis  at  the  inner  canthus,  descending 
along  the  edge  of  the  groove  for  the  lachrymal  sac. 

The  first  and  shortest  portion  is 

Inserted  into  the  upper  lip  and  orbicularis  labiorum ;  the 
second  and  longest,  into  the  upper  lip  and  outer  part  of  the  ala 
nasi. 

Use.  To  raise  the  upper  lip  towards  the  orbit,  and  a  little 
outwards  ;  the  second  portion  serves  to  draw  the  skin  of  the 
nose  upwards  and  outwards,  by  which  the  nostril  is  dilated. 

3.    Depressor  Labii  Superioris  Alceque  Nasi, 

Arises,  thin  and  fleshy,  from  the  os  maxillare  superius,  imme- 
diately above  the  joining  of  the  gums  with  the  two  denies  inci- 
sores  and  the  dens  caninus ;  from  thence  it  runs  up  under  part 
of  the  levator  labii  superioris  alaeque  nasi. 

Inserted  into  the  upper  lip  and  root  of  the  ala  nasi. 

Use.  To  draw  the  upper  lip  and  ala  nasi  downwards  and 
backwards. 

The  three  below  are, 

1.  Depressor  Anguli  Oris, 

Arises,  broad  and  fleshy,  from  the  lower  edge  of  the  maxilla 
inferior,  at  the  side  of  the  chin,  being  firmly  connected  to  that 
part  of  the  platysma  myoides,  which  runs  over  the  maxilla  to 
the  angle  of  the  mouth,  to  the  depressor  labii  inferioris  within, 
and  to  the  skin  and  fat  without,  gradually  turning  narrower ; 
and  is 

Inserted  into  the  angle  of  the  mouth,  joining  with  the  zygo- 
maticus  major  and  levator  anguli  oris. 

Use.   To  pull  down  the  corner  of  the  mouth. 

2.  Depressor  Labii  Inferioris, 

Arises,  broad  and  fleshy,  interiflixed  with  fat,  from  the  infe- 


MUSCLES  OF    THE  FACE, 


309 


rior  part  of  the  lower  jaw  next  to  the  chin  ;  runs  obliquely 
upwards,  and  is 

Inserted  into  the  edge  of  the  under  lip,  extends  along  OJEIC  half 
of  the  lid,  and  is  lost  in  its  red  part. 

Use.  To  pull  the  under  lip  and  the  skin  of  the  side  of  the 
chin  downwards,  and  a  little  outwards. 


Fig.  78.* 


3.  Levator  Labii  Inferioris, 

Arises,  from  the  lower  jaw,  at 
the  roots  of  the  alveoli  of  two 
denies  incisores  and  of  the  cani- 
nus  ;  is 

Inserted  into  the  under  lip 
and  skin  of  the  chin. 

Use.  To  pull  the  parts,  into 
which  it  is  inserted,  upwards. 

The  three  outward  are, 

1.  Buccinator, 


Arises,  tendinous  and  fleshy, 
from  the  lower  jaw,  as  far  back 
as  the  last  dens  molaris  and  forepart  of  the  root  of  the  coronoid 
process ;  fleshy  from  the  upper  jaw,  between  the  last  dens  mo- 
laris and  pterygoid  process  of  the  sphenoid  bone ;  from  the 
extremity  of  this  process  it  arises  tendinous,  being  continued 
between  both  jaws  to  the  constrictor  pharyngis  superior,  with 
which  it  joins  ;  from  thence,  proceeding  with  straight  fibres, 
and  adhering  close  to  the  membrane  that  lines  the  mouth,  it  is 

Inserted  into  the  angle  of  the  mouth  within  the  orbicularis 
oris. 

Use.  To  draw  the  angle  of  the  mouth  backwards  and  out- 
wards, and  contract  its  cavity,  by  pressing  the  cheek  inwards, 
by  which  the  food  is  thrust  between  the  teeth.  — The  bucci- 

*  a,  Depressor  labii  inferioris.  b,  Buccinator,  c,  Levator  anguli  oris.  e, 
Levator  labii  inferioris  (levator  menti ;)  this  will  be  best  seen  in  dissection  by 
inverting  the  lip  and  dissecting  off  the  mucous  membrane.  /,  Depressor  anguli 
oris.  5,  Masseter.  g,  Tendon  of  the  superior  or  internal  oblique  muscle  of 
the  eye,  after  it  passes  its  trochlea.  h,  Inferior  oblique. 


310  MUSCLES  OF    THE  FACE. 

nator  acts  principally  in  front  on  the  commissure  of  the  lips, 
which  it  draws  backwards  horizontally,  increasing  transversely 
the  aperture  of  the  mouth,  and  throwing  the  cheek  into  the 
vertical  folds,  so  conspicuous  in  old  age.  It  thus  antagonizes 
the  orbicularis  oris.  If  both  these  muscles  act  together,  the 
lips  are  extended  and  pressed  against  the  teeth.  When  the 
cavity  of  the  mouth  is  distended  with  air  or  liquids,  the  fibres 
of  this  muscle  are  protruded  and  curved.  If  the  muscle  now 
acts,  the  fibres  become  straightened,  and  the  fluid  is  expelled 
from  the  mouth,  suddenly  or  gradually,  according  to  the  resist- 
ance made  by  the  orbicularis. 

— This  muscle  assists  also  in  mastication  and  deglutition,  by 
pressing  the  food  from  between  the  cheek  and  gums  into  the 
cavity  of  the  mouth. — 

2.  Zygomaticus  Major, 

Arises,  fleshy,  from  the  os  malae,  near  the  zygomatic  suture. 

Inserted  into  the  angle  of  the  mouth,  appearing  to  be  lost  in 
the  depressor  anguli  oris  and  orbicularis  oris. 

Use.  To  draw  the  corner  of  the  mouth  and  under  lip 
towards  the  origin  of  the  muscle,  and  make  the  cheek  promi- 
nent, as  in  laughing. 

2.    Zygomaticus  Minor, 

Arises  from  the  upper  prominent  part  of  the  os  malae,  above 
the  origin  of  the  former  muscle  ;  and,  descending  obliquely 
downwards  and  forwards,  is 

Inserted  into  the  upper  lip,  near  the  corner  of  the  mouth, 
along  with  the  levator  anguli  oris. 

Use.  To  draw  the  corner  of  the  mouth  obliquely  outwards 
and  upwards  towards  the  external  canthus  of  the  eye. 

The  common  muscle  is  the 

Orbicularis   Oris. 

This  muscle  is,  in  a  great  measure,  formed  by  the  muscles 
that  move  the  lips ;  the  fibres  of  the  superior  descending,  those 


MUSCLES  OF    THE  LOWER  JAW.  311 

of  the  inferior  ascending,  and  decussating  each  other  about  the 
corner  of  the  mouth,  run  along  the  lip  to  join  those  of  the  oppo- 
site side,  so  that  the  fleshy  fibres  appear  to  surround  the^mouth 
like  a  sphincter. 

Use.  To  shut  the  mouth,  by  contracting  and  drawing  both 
lips  together,  and  to  counteract  all  the  muscles  that  assist  in 
forming  it. 

There  is  another  small  muscle  described  by  Albinus,  which  he 
calls  Nasalis  labii  superioris ;  but  it  seems  to  be  only  some 
fibres  of  the  former  connected  to  the  septum  nasi. 

— The  orbicularis,  possesses  a  very  varied  and  extensive  action, 
and  may  act  as  a  whole  or  in  parts.  Its  simplest  action  is  to 
close  the  mouth  by  bringing  the  lips  together.  The  upper  or 
lower  labial  fibres  may  act  separately,  as  well  as  those  at  the 
commissures  of  the  lips,  by  which  they  are  enabled  in  turn,  to 
antagonize  the  different  muscles,  which  are  attached  around.  By 
a  very  strong  contraction  of  the  labial  and  commissural  fibres, 
the  lips  are  thrown  forwards  in  a  circular  projection,  as  in  whist- 
ling. By  the  contraction  of  the  inner  labial  fibres,  they  are 
drawn  inwards  upon  the  teeth. — 

Muscles  of  the  Lower  Jaw. 

The  lower  jaw  has  four  pair  of  muscles  for  its  elevation  or 
lateral  motions,  namely,  two,  which  are  seen  on  the  side  of  the 
face,  and  two  concealed  by  the  angle  of  the  jaw. 

1.   Temporalis, 

Arises,  fleshy,  from  a  semicircular  ridge  of  the  lower  and 
lateral  part  of  the  parietal  bone,  from  all  the  pars  squamosa  of 
the  temporal  bone,  from  the  external  angular  process  of  the  os 
frontis,  from  the  temporal  process  of  the  sphenoid  bone,  and 
from  an  aponeurosis  which  covers  it ;  from  these  different  origins 
the  fibres  descend  like  radii  towards  the  jugum,  under  which 
they  pass ;  and  are, 

Inserted,  by  a  strong  tendon,  into  the  upper  part  of  the  coro- 
noid  process  of  the  lower  jaw  ;  in  the  duplicature  of  which  ten- 


312  MUSCLES  OF    THE  LOWER  JAW. 

don  this  process  is  enclosed  as  in  a  sheath,  being  continued 
down  all  its  forepart  to  near  the  last  dens  molaris. 

Use.  To  pull  the  lower  jaw  upwards,  and  press  it  against 
the  upper,  at  the  same  time  drawing  it  a  little  backwards. 

N.  B.  This  muscle  is  covered  with  a  tendinous  membrane, 
called  its  aponeurosis,  which  arises  from  the  bones  that  give 
origin  to  the  upper  and  semicircular  part  of  the  muscle ;  and 
descending  over  it,  is  inserted  into  all  the  jugum,  and  the 
adjoining  part  of  the  os  fronds. 

The  use  of  this  membrane  is  to  give  room  for  the  origin  of  a 
greater  number  of  fleshy  fibres,  to  fortify  the  muscle  in  its 
action,  and  to  serve  as  a  defence  to  it. 

2.  Masseter, 

Arises,  by  strong,  tendinous,  and  fleshy  fibres,  which  run  in 
different  directions,  from  the  superior  maxillary  bone,  where  it 
joins  the  os  malae,  and  from  the  inferior  and  anterior,  part  of  the 
zygoma,  its  whole  length,  the  external  fibres  slanting  backwards, 
and  the  internal  forwards. 

Inserted  into  the  angle  of  the  lower  jaw,  and  from  that 
upwards  to  near  the  top  of  its  coronoid  process. 

Use.  To  pull  the  lower  to  the  upper  jaw,  and  by  means  of 
its  oblique  decussation,  a  little  forwards  and  backwards. 

3.  Pterygoideus  Internus, 

Arises,  tendinous  and  fleshy,  from  the  inner  and  upper  part  of 
the  internal  plate  of  the  pterygoid  process,  filling  all  the  space 
between  the  two  plates ;  and  from  the  pterygoid  process  of  the 
os  palati  between  these  plates. 

Inserted  into  the  angle  of  the  lower  jaw  internally. 

Use.  To  draw  the  jaw  upwards,  and  obliquely  towards  the 
opposite  side. 

4.  Pterygoideus  Externus, 

Arises  from  the  outer  side  of  the  external  plate  of  the  ptery- 
goid process  of  the  sphenoid  bone,  from  part  of  the  tuberosity  of 
the  os  maxillare  adjoining  to  it,  and  from  the  root  of  the  tempo- 
ral process  of  the  sphenoid  bone. 


MUSCLES  OF  THE  NECK.  313 

Fig.  79.*  Inserted  into  the  cavity  in  the 

neck  of  the  condyloid  process  of 
the  lower  jaw  ;  some  of  Hs  fibres 
are  inserted  into  the  ligament 
that  connects  the  movable  carti- 
lage and  that  process  to  each 
other. 

Use.  To  pull  the  lower  jaw 
forwards,  and  to  the  opposite 
side ;  and  to  pull  the  ligament 
from  the  joint,  that  it  may  not 

be  pinched  during  these  motions  :  when  both  external  ptery- 
goid  muscles  act,  the  fore  teeth  of  the  under  jaw  are  pushed 
forwards  beyond  those  of  the  upper  jaw. 

The  Muscles  which  appear  about  the  anterior  part  of  the  Neck. 
On  the  side  of  the  neck  are  two  muscles,  or  layers. 

1.  Musculus  Cutaneus,  vulgo  Platysma  Myoides,  (see  fig.  75,)    / 

Arises,  by  a  number  of  slender  separate  fleshy  fibres,  from 
the  cellular  substance  that  covers  the  upper  part  of  the  deltoid 
and  pectoral  muscles ;  in  their  ascent  they  all  unite  to  form  a 
thin  muscle,  which  runs  obliquely  upwards  along  the  side  of  the 
neck,  adhering  to  the  skin. 

Inserted  into  the  lower  jaw,  between  its  angle  and  the  origin 
of  the  depressor  anguli  oris,  to  which  it  is  firmly  connected,  and 
but  slightly  to  the  skin  that  covers  the  inferior  part  of  the  mas- 
seter  muscle  and  parotid  glands. 

Use.  To  assist  the  depressor  anguli  oris,  in  drawing  the  skin 
of  the  cheek  downwards  ;  and  when  the  mouth  is  shut,  it  draws 
all  that  part  of  the  skin,  to  which  it  is  connected,  below  the 
lower  jaw,  upwards. — Some  of  its  fibres  are  inserted  into 
the  angle  of  the  mouth,  and  are  connected  with  the  muscles  of 

*  The  two  pterygoid  muscles.  The  zygomatic  arch  and  the  greater  part  of 
the  ramus  of  the  lower  jaw  have  been  removed  in  order  to  bring  these  muscles 
into  view.  1.  The  sphenoid  origin  of  the  external  pterygoid  muscle.  2.  Its 
pterygoid  origin.  3.  The  internal  pterygoid  muscle. 

27 


314 


MUSCLES  OF  THE  NECK. 


that  region.     They  draw  the  corner  of  the  mouth  downwards, 
and  constitute  the  musculus  risorius  of  Santorini. — 

2.  Sterno-cleido-mastoideus, 

Arises  by  two  distinct  origins  : 
the  anterior  tendinous  and  a 
little  fleshy,  from  the  top  of  the 
sternum  near  its  junction  with 
the  clavicle ;  the  posterior, 
fleshy,  from  the  upper  and  an- 
terior part  of  the  clavicle  ;  both 
unite  a  little  above  the  ante- 
rior articulation  of  the  clavicle, 
to  form  one  muscle,  which  runs 
obliquely  upwards  and  out- 
wards, to  be 

Inserted,  by   a    thick   strong 
tendon,  into   the   mastoid    pro- 
cess, which   it  surrounds ;    and,   gradually  turning  thinner,   is 
inserted  as  far  back  as  the  lambdoid  suture. 

Use.  To  turn  the  head  to  one  side,  and  bend  it  forwards. 

Muscles  situated  between  the  Lower  Jaw  and  Os  Hyoides. 

There  are  four  layers  before,  and  two  muscles  at  the  side. 
The  four  layers  are, 

1.  Digastricus,  (see  fig.  78,) 

Arises,  by  a  fleshy  belly,  intermixed  with  tendinous  fibres, 
from  the  fossa  at  the  root  of  the  mastoid  process  of  the  temporal 
bone,  and  soon  becomes  tendinous ;  runs  downwards  and  for- 
wards :  the  tendon  passes  generally  through  the  stylo-hyoideus 
muscle ;  then  it  is  fixed  by  a  ligament  to  the  os  hyoides ;  and, 
having  received  from  that  bone  an  addition  of  tendinous  and 
muscular  fibres,  runs  obliquely  forwards,  turns  fleshy  again, 
and  is 

*  b,  Buccinator,  d,  Depressor  labii  inferioris.  h,  Corrugator  Supercilii. 
n,  Compressor  naris.  5,  Sterno-cleido-mastoid.  t,  Temporal,  u,  Trapezius. 
v,  Splenius  capitis.  v,  Splenius  colli.  x,  Digastricus.  y,  Mylo-hyoid.  z,  Stylo 
hyoid.  &,  Hyo-glossus. 

••e^£L'&     ^JA    s4f*,+^ 


MUSCLES  OF  THE  NECK.  315 

Inserted,  by  its  anterior  belly,  into  a  rough  sinuosity  at  the 
inferior  and  anterior  edge  of  that  part  of  the  lower  jaw  called 
the  chin. 

Use.  To  open  the  mouth  by  pulling  the  lower  jaw  down- 
wards, and  backwards ;  and  when  the  jaws  are  shut,  to  raise 
the  os  hyoides,  and,  consequently,  the  pharynx,  upwards,  as  in 
deglutition. 

2.  Mylo'Hyoideus,(Seefig'lS,) 

Arises,  fleshy,  from  all  the  inside  of  the  lower  jaw,  between, 
the  last  dens  molaris  and  the  middle  of  the  chin,  where  it  joins 
with  its  fellow. 

Inserted  into  the  lower  edge  of  the  basis  of  the  os  hyoides, 
and  joins  with  its  fellow. 

Use.  To  pull  the  os  hyoides  forwards,  upwards,  and  to  one 
side. 

3.  Genio-Hyoideus, 

Arises,  tendinous,  from  a  rough  protuberance  in  the  middle  of 
the  lower  jaw  internally,  or  on  the  inside  of  the  chin. 
Inserted  into  the  basis  of  the  os  hyoides. 
Use.    To  draw- this  bone  forwards  to  the  chin. 

4.  Genio-Hyo-Glossus. 

Arises,  tendinous,  from  a  rough  protuberance  in  the  inside  of 
the  middle  of  the  lower  jaw  ;  its  fibres  run  like  a  fan,  forwards, 
upwards,  and  backwards ;  and  are 

Inserted  into  the  whole  length  of  the  tongue,  and  base  of  the 
os  hyoides,  near  its  cornu. 

Use.  According  to  the  direction  of  its  fibres,  to  draw  the  tip 
of  the  tongue  backwards  into  the  mouth,  the  middle  down- 
wards, and  to  render  its  dorsum  concave  ;  to  draw  its  root  and 
os  hyoides  forwards,  and  to  thrust  the  tongue  out  of  the  mouth. 

The  two  muscles  at  the  side  are, 

1.  Hyo-Glossus, 

Arises,  broad  and  fleshy,  from  the  base,  cornu,  and  appendix, 
of  the  os  hyoides ;  the  fibres  run  upwards  and  outwards ;  to  be 


f 


316  MUSCLES  OF  THE  NECK. 

Inserted  into  the  side  of  the  tongue,  near  the  stylo-glossus. 
Use.     To  pull  the  tongue  inwards  and  downwards. 

2.  Lingualis, 

Arises  from  the  root  of  the  tongue  laterally  ;  runs  forwards 
between  the  hyo-glossus  and  genio-glossus,  to  be 

Inserted  into  the  tip  of  the  "tongue,  along  with  part  of  the 
atylo-glossus. 

Use.  To  contract  the  substance  of  the  tongue,  and  bring  ii 
backwards,  and  to  elevate  the  point  of  the  tongue. 

9'  JT  - 

-  ••!  • 

Muscles  situated  between  the  Os  Hyoides  and  Trunk. 

These  may  be  divided  into  two  layers. 
The  first  layer  consists  of  two  muscles, 

1 .   Sterno-Hyoideus,     , 

Arises,  thin  and  fleshy,  from  the  cartilaginous  extremity  of 
the  first  rib,  the  upper  and  inner  part  of  the  sternum,  and  from 
the  clavicle  where  it  joins  with  the  sternum. 

Inserted  into  the  base  of  the  os  hyoides. 

Use.    To  pull  the  os  hyoides  downwards. 

i 

v  2.    Omo-Hyoideus, 

Arises,  broad,  thin,  and  fleshy,  from  the  superior  costa  of  the 
scapula,  near  the  semilunar  notch,  and  from  the  ligament  that 
runs  across  it ;  thence  ascending  obliquely,  it  becomes  tendinous 
below  the  sterno-cleido-mastoid  muscle ;  and,  growing  fleshy 
again,  is 

Inserted  into  the  base  of  the  os  hyoides,  between  its  comu 
and  the  insertion  of  the  sterno-hyoideus. 

Use.    To  pull  the  os  hyoides  obliquely  downwards. 

The  second  layer  consists  of  three  muscles. 

1 .  Sterno-  Thyroideus3 

Arises,  fleshy,  from  the  whole  edge  of  the  uppermost  bone 
of  the  sternum  internally,  opposite  to  the  cartilage  of  the 
rib,  from  which  it  receives  a  small  part  of  its  origin. 


MUSCLES  BETWEEN  THE  JAW  AND    OS  HYOIDES.  317 

Inserted  into  the  surface  of  the  rough  line  at  the  external  part 
of  the  inferior  edge  of  the  thyroid  cartilage. 
Use.    To  draw  the  larynx  downwards. 

2.    Thyro-Hyoideus, 

Arises  from  the  rough  line  opposite  to  the  insertion  of  the 
former  muscle. 

Inserted  into  part  of  the  basis,  and  almost  all  the  cornu  of 
the  os  hyoides. 

Use.  To  pull  the  os  hyoides  downwards,  or  the  thyroid  car- 
tilage upwards. 

3.   Crico-Thyroideus , 
Which  will  be  described  with  the  larynx  :  Chap.  xiv. 

Muscles   situated  between   the  Lower   Jaw   and    Os   Hyoides 

laterally. 

They  are  five  in  number.  They  proceed  three  from  the  styloid 
process  of  the  temporal  bone,  from  which  they  have  half  of 
their  names  ;  and  two  from  the  pterygoid  process  of  the  sphe- 
noid bone. 

The  three  from  the  styloid  process  are, 

1 .    Stylo-Glossusj 

Arises,  tendinous  and  fleshy,  from  the  styloid  process,  and 
from  a  ligament  that  connects  that  process  to  the  angle  of  the 
lower  jaw. 

Inserted  into  the  root  of  the  tongue,  runs  along  its  side,  and  is 
insensibly  lost  near  its  apex. 

Use.    To  draw  the  tongue  laterally  and  backwards. 

2.  Stylo- Hyoideusj 

Arises,  by  a  round  tendon,  from  the  middle  and  inferior  part 
of  the  styloid  process. 

Inserted  into  the  os  hyoides  at  the  junction  of  the  base  and 
cornu. 

Use.    To  pull  the  os  hyoides  to  one  side,  and  a  little  upwards 
27* 


319  MUSCLES  OF  THE  PALATE. 

N.  B.  Its  fleshy  belly  is  generally  perforated  by  the  tendon 
of  the  digastric  muscle,  on  one  or  both  sides.  There  is  often 
another  accompanying  it,  called  stylo -hyoideus  alter ;  and  has 
the  same  origin,  insertion,  and  use. 

3.   Stylo-Pharyngeus, 

Arises,  fleshy,  from  the  root  6*f  the  styloid  process. 

Inserted  into  the  side  of  the  pharynx  and  back  part  of  the 
thyroid  cartilage. 

Use.  To  dilate  the  pharynx  and  raise  it  and  the  thyroid 
cartilage  upwards. 

The  two  from  the  pterygoid  process  are, 

1.    Circumflexus,  or  Tensor  Palati, 

Arises  from  the  spinous  process  of  the  sphenoid  bone,  behind 
the  foramen  ovale,  which  transmits  the  third  branch  of  the  fifth 
pair  of  nerves,  from  the  Eustachian  tube,  not  far  from  its  osse- 
ous part ;  it  then  runs  down  along  the  pterygoideus  internus, 
passes  over  the  hook  of  the  internal  plate  of  the  pterygoid 
process  by  a  round  tendon,  which  soon  spreads  into  a  broad 
membrane. 

Inserted  into  the  velum  pendulum  palati,  and  the  semilunar 
edge  of  the  os  palati,  and  extends  as  far  -as  the  suture  which 
joins  the  two  bones.  Generally  some  of  its  posterior  fibres  join 
with  the  constrictor  pharyngis  superior,  and  palato-pharyngeus. 

Use.  To  stretch  the  velum,  to  draw  it  downwards,  and  to  one 
side  towards  the  hook.  It  has  little  effect  upon  the  tube,  being 
chiefly  connected  to  its  osseous  part. 

2.  Levator  Palati, 

Arises,  tendinous  and  fleshy,  from  the  extremity  of  the  pars 
petrosa  of  the  temporal  bone,  where  it  is  perforated  by  the 
Eustachian  tube,  and  also  from  the  membranous  part  of  the 
same  tube. 

Inserted  into  the  whole  length  of  the  velum  pendulum 
palati,  as  far  as  the  root  of  the  uvula,  and  unites  with  its 
fellow. 


MUSCLES    OF    THE  FAUCES.  319 

Use.  To  draw  the  velum  upwards  and  backwards,  so  as  to 
shut  the  passage  from  the  fauces  into  the  mouth  and  nose. 

^ 
Muscles  situated  about  the  passage  of  the  Fauces. 

There  are  two  on  each  side,  and  a  single  one  in  the  middle. 
The  two  on  each  side  are, 

1.    Constrictor  Isthmi  Faucium, 

Arises,  by  a  slender  beginning,  from  the  side  of  the  tongue, 
near  its  root ;  thence  running  upwards  within  the  anterior  arch, 
before  the  amygdala,  it  is 

Inserted  into  the  middle  of  the  velum  pendulum  palati,  at  the 
root  of  the  uvula  anteriorly,  being  connecte'd  with  its  fellow,  and 
with  the  beginning  of  the  palato-pharyngeus. 

Use.  Draws  the  velum  towards  the  root  of  the  tongue,  which 
it  raises  at  the  same  time,  and  with  its  fellow,  contracts  the 
passage  between  the  two  arches,  by  which  it  shuts  the  opening 
into  the  fauces. 

2.  Palato-Pharyngeus, 

Arises,  by  a  broad  beginning,  from  the  middle  of  the  velum 
palati,  at  the  root  of  the  uvula  posteriorly,  and  from  the  ten- 
dinous expansion  of  the  circumflexus  palati.  The  fibres  are 
collected  within  the  posterior  arch  behind  the  amygdala,  and 
run  backwards  to  the  top  and  lateral  part  of  the  pharynx,  where 
the  fibres  are  scattered,  and  mix  with  those  of  the  stylo-pha- 
ryngeus. 

Inserted  into  the  edge  of  the  upper  and  back  part  of  the  thy- 
roid cartilage  ;  some  of  the  fibres  being  lost  between  the  mem- 
brane of  the  pharynx,  and  the  two  inferior  constrictors. 

Use.  Draws  the  uvula  and  velum  downwards  and  backwards  : 
and,  at  the  same  time,  pulls  the  thyroid  cartilage  and  pharynx 
upwards,  and  shortens  it ;  with  the  constrictor  superior  and 
tongue,  it  assists  in  shutting  the  passage  into  the  nostrils  ;  and. 
in  swallowing,  it  thrusts  the  food  from  the  fauces  into  the 
pharynx. 


320  MUSCLES  OF  THE  FAUCES. 


Salpingo-Pharyngenus,  (from  salnd^  trumpet,') 

Of  Albinus,  is  composed  of  a  few  fibres  of  this  muscle,  which 
Arise  from   the  anterior  and   lower  part  of  the  cartilaginous 
extremity  of  the  Eustachian  tube  ;  and  are, 

Inserted  into  the  inner  part  of  the  last-mentioned  muscles. 
Use.    To  assist  the  former,  and  to  dilate  the  mouth  of  the  tube. 
The  one  in  the  middle  is  the 

Azygos  Uvula, 

Arises,  fleshy,  from  the  extremity  of  the  suture  which  joins 
the  palate  bones,  runs  down  the  whole  length  of  the  velum  and 
uvula,  resembling  a  small  earth-worm,  and  adhering  to  the  ten- 
dons of  the  circumflexi.  Two  are  frequently  met  with. 

Inserted  into  the  apex  of  the  uvula. 

Use.    Raises  the  uvula  upwards  and  forwards,  and  shortens  it. 

Muscles  situated  on  the  posterior  part  of  the  Pharynx. 
Of  these  there  are  three  pair  : 

1.    Constrictor  Paryngis  Inferior, 

Arises,  from  the  side  of  the  thyroid  cartilage,  near  the  attach- 
ment of  the  thyroideus  and  thyro-hyoideus  muscles  ;  and  from 
the  cricoid  cartilage,  near  the  crieo-thyroideus.  This  muscle  is 
the  largest  of  the  three  ;  and  is 

Inserted  into  the  white  line,  where  it  joins  with  its  fellow  : 
the  superior  fibres  running  obliquely  upwards,  covering  nearly 
one  half  of  the  middle  constrictor,  and  terminating  in  a  point  ; 
the  inferior  fibres  run  more  transversely  and  covers  the  beginning 
of  the  oesophagus. 

Use.  To  compress  that  part  of  the  pharynx  which  it  covers, 
and  to  raise  it  with  the  larynx  a  little  upwards. 

2.    Constrictor  Pharyngis  Medius, 

Arises  from  the  appendix  of  the  os  hyoides,  from  the  cornu 
of  that  bone,  and  from  the  ligament  which  connects  it  to  the 
thyroid  cartilage  ;  the  fibres  of  the  superior  part  running 


MUSCLES  OF  THE  GLOTTIS.  321 

obliquely  upwards,  and,  covering  a  considerable  part  of  the 
superior  constrictor,  terminate  in  a  point. 

Inserted  into  the  middle  of  the  cuneiforme  process  oFthe  os 
occipitis,  before  the  foramen  magnum,  and  joined  to  its  fellow 
at  a  white  line  in  the  middle  back  part  of  the  pharynx.  The 
fibres  at  the  middle  part  run  more  transversely  than  those  above 
or  below. 

Use.  To  compress  that  part  of  the  pharynx  which  it  covers, 
and  to  draw  it  and  the  os  hyoides  upwards. 

3.    Constrictor  Pharyngis  Superior, 

Arises,  above,  from  the  cuneiforme  process  of  the  os  occi- 
pitis, before  the  foramen  magnum,  near  the  holes  where  the 
ninth  pair  of  the  nerves  passes  out ;  lower  down,  from  the 
pterygoid  process  of  the  sphenoid  bone  ;  from  the  upper  and 
under  jaw,  near  the  roots  of  the  last  dentes  molares ;  and 
between  the  jaws,  it  is  continued  with  the  buccinator  muscle  ; 
and  with  some  fibres  from  the  root  of  the  tongue,  and  from  the 
palate. 

Inserted  into  a  white  line  in  the  middle  of  the  pharynx, 
where  it  joins  with  its  fellow,  and  is  covered  by  the  constrictor 
medius. 

Use.  To  compress  the  upper  part  of  the  pharynx,  and  draw 
it  forwards  and  upwards.  See  article,  pharynx. 

Muscles  situated  about  the  Glottis. 

They  consist  generally  of  four  pair  of  small  muscles,  and  a 
single  one.  See  Larynx,  chapt.  xiv. 

Muscles  situated  on  the  Anterior  Part  of  the  Neck,  close  to  the 
Vertebra.     (Pravertebral  Muscles.) 

These  consist  of  one  layer,  formed  by  four  muscles. 

1.    Longus  Colli, 

Arises,  tendinous  and  fleshy  from  the  bodies  of  the  three 
vertebrae  of  the  back  laterally  ;  and  from  the  transverse  process 
of  the  third,  fourth,  fifth,  and  sixth  vertebrae  of  the  neck,  near 
their  roots. 


322 


MUSCLES  OF    THE  SIDE  OF    THE  NECK. 


Inserted  into  the  forepart  of  the  bodies  of  all  the  vertebrae  of 
the  neck,  by  as  many  small  tendons,  which  are  covered  with 
flesh. 

Use.    To  bend  the  neck  gradually  forwards,  and  to  one  side. 

2.  Rectus  Capitis  Internus  Major, 

Arises  from  the  anterior  points  of  the  transverse  process  of 
the  third,  fourth,  fifth,  and  sixth  vertebrae  of  the  neck,  by  four 
distinct  beginnings. 

Inserted  into  the  cuneiforme  process  of  the  os  occipitis,  a  little 
before  the  condyloid  process. 

Use.    To  bend  the  head  forwards. 

3.  Rectus  Capitis  Internus  Minor, 

Arises,  fleshy,  from  the  forepart  of  the  body  of  the  first  ver- 
tebra of  the  neck  opposite  to  the  Fig.  81.* 
superior  oblique  process. 

Inserted  near  the  root  of  the 
condyloid  process  of  the  os  occi- 
pitis, under,  and  a  little  farther  out- 
wards, than  the  former  muscle. 

Use.  To  bend  the  head  forwards. 

4.  Rectus  Capitis  Lateralis, 

Arises,  fleshy,  from  the  anterior 
part  of  the  point  of  the  transverse 
process  of  the  first  vertebra  of  the 
neck. 

Inserted  into  the  os  occipitis, 
opposite  to  the  foramen  stylo-mas- 
toideum  of  the  temporal  bone. 

Use.  To  bend  the  head  a  little 
to  one  side. 

*  The  prse vertebral  group  of  muscles  of  the  neck.  1.  The  rectus  anticus 
major  muscle.  2.  The  scalenus  anticus.  3.  The  lower  part  of  the  longuscolli 
of  the  right  side  ;  it  is  concealed  superiorly  by  the  rectus  anticus  major.  4. 
The  rectus  anticus  minor.  5.  The  upper  portion  of  the  longus  colli  muscle. 
6.  Its  lower  portion  ;  the  figure  rests  upon  the  seventh  cervical  vertebra.  7.  The 
scalenus  posticus.  8.  The  rectus  lateralis  of  the  left  side.  9.  One  of  the 
intertr  an  oversales  muscles. 


MUSCLES  OF  THE  THORAX.  323 

Muscles  situated  on  the  Anterior  Part  of  the  Thorax. 

These  may  be  divided  into  two  layers.  The  first  laye/  con- 
sists of  one  muscle,  named 

Pectoralis  Major, 

Arises  from  the  cartilaginous  extremities  of  the  fifth  and 
sixth  ribs,  where  it  always  intermixes  with  the  external 
oblique  muscle  of  the  abdomen ;  from  almost  the  whole  length 
of  the  sternum  :  and  from  near  half  of  the  anterior  part  of  the 
clavicle ;  the  fibres  run  towards  the  axilla  in  a  folding  manner. 

Inserted,  by  two  broad  tendons,  which  cross  each  other  at 
the  upper  and  inner  part  of  the  os  humeri,  above  the  insertion 
of  the  deltoid  muscle,  and  outer  side  of  the  groove  for  lodging 
the  tendon  of  the  long  head  of  the  biceps. 

Use.  To  move  the  arm  forwards,  and  obliquely  upwards, 
towards  the  sternum. 

The  second  layer  consists  of  three  muscles.      . 

/^    J^^     •/? 

1 .    Subdavius, 

Arises,  tendinous,  from  the  cartilage  that  joins  the  first  rib  to 
the  sternum. 

Inserted,  after  becoming  fleshy,  into  the  inferior  part  of  the 

clavicle,  which  it  occupies  from  within  an  inch  of  the  sternum, 

as  far  outwards  as  to  its  connexion,  by  ligament,  with  the 
coracoid  process  of  the  scapula. 

Use.  To  pull  the  clavicle  downwards  and  forwards. 

2.    Pectoralis  Minor, 

Arises,  tendinous  and  fleshy,  from  the  upper  edge  of  the 
third,  fourth,  and  fifth  ribs,  near  where  they  join  with  their 
cartilages. 

Inserted,  tendinous,  into  the  coracoid  process  of  the  scapula  : 
but  soon  grows  fleshy  and  broad. 

Use.  To  bring  the  scapula  forwards  and  downwards,  or  to 
raise  the  ribs  upwards. 


324  MUSCLES  OF    THE  THORAX. 

3.    Serratus  Magnus, 

Arises  from  the  nine  superior  ribs,  by  an  equal  number  of 
fleshy  digitations,  resembling  the  teeth  of  a  saw. 

Inserted,  fleshy,  into  the  whole  base  of  the  scapula  internally, 
between  the  insertion  of  the  rhomboid  and  the  origin  of  the 
subscapularis  muscle,  being  folded  about  the  two  angles  of  the 
scapula. 

Use.  To  move  the  scapula  forwards  :  and,  when  the  scapula 
is  forcibly  raised,  to  draw  upwards  the  ribs.  ^ 

Muscles  situated  between  the  Ribs,  and  within  the  Thorax. 

Between  the  ribs,  on  each  side,  there  are  eleven  double  rows 
of  muscles,  which  are,  therefore,  named  intercostals.  These 
decussate  each  other  like  the  strokes  of  the  letter  X. 

1.  Intercostaks  Eocterni, 

Arise  from  the  inferior  acute  edge  of  each  superior  rib,  and 
run  obliquely  forwards,  the  whole  length  from  the  spine  to 
near  the  joining  of  the  ribs  with  their  cartilages ;  from  which, 
to  the  sternum,  there  is  only  a  thin  membrane  covering  the 
internal  intercostals. 

Inserted  into  the  upper  obtuse  edge  of  each  inferior  rib,  as 
ar  back  as  the  spine,  into  which  the  posterior  portion  is  fixed. 

2.  Intcrcostales  Interni, 

Arise  in  the  same  manner  as  the  external :  but  they  begin  at 
the  sternum,  and  run  obliquely  backwards,  as  far  as  the  angle 
of  the  rib  ;  and  from  that  to  the  spine  they  are  wanting. 

Inserted  in  the  same  manner,  as  the  external. 

Use.  By  means  of  these  muscles,  the  ribs  are  equally  raised 
upwards,  during  inspiration.  Their  fibres  being  oblique,  give 
them  a  greater  power  of  bringing  the  ribs  near  each  other,  than 
could  be  performed  by  straight  ones.  By  the  obliquity  of 
the  fibres,  they  are  almost  brought  contiguous  :  and  as  the  fixed 
points  of  the  ribs  are  before  and  behind,  if  the  external  had 
been  continued  forwards  to  the  sternum,  and  the  internal 


ABDOMINAL  MUSCLES,  325 

backwards  to  the  spine,  it  would  have  hindered  their  motion, 
which  is  greatest  in  the  middle,  though  the  obliquity  of  the 
ribs  renders  it  less  perceptible ;  and,  instead  of  raising  th#  fibres 
fixed  to  the  sternum  and  spine,  would  have  depressed  the  ribs, 

N.  B.  The  portions  of  the  external  intercostals,  which  arise 
from  the  transverse  processes  of  the  vertebrae  where  the  ribs 
are  fixed  to  them,  and  other  portions  that  pass  over  one  rib 
and  terminate  in  the  next  below  it,  Albinus  calls  Levatores 
costarum  longiores  et  breviores* 

The  portions  of  the  internal  that  pass  over  one  rib,  and  are 
inserted  into  the  next  below  it,  are,  by  Douglas,  called 
Costarum  depressores  proprii  Cowperi. 

These  portions  of  both  rows  assist  in  raising  the  ribs  in  the 
same  manner  as  the  rest  of  the  intercostals. 

The  muscles  within  the  thorax  form  one  pair,  viz. 

Triangularis,  or  Stemo-Costalis, 

Arises,  fleshy,  and  a  little  tendinous,  from  all  the  length  of 
the  cartilago-ensiformis  laterally,  and  from  the  edge  of  the 
lower  half  of  the  middle  bone  of  the  sternum,  from  whence  its 
fibres  ascend  obliquely  upwards  and  outwards, 

Inserted,  generally  by  three  triangular  terminations,  into  the 
lower  edge  of  the  cartilages  of  the  third,  fourth,  and  fifth  ribs ; 
near  where  these  join  with  the  ribs. 

Use.  To  depress  these  cartilages,  and  the  extremities  of  the 
ribs ;  and  consequently  to  assist  in  contracting  the  cavity  of  the 
thorax. 

This  muscle  often  varies ;  and  is  sometimes  inserted  into  the 
cartilage  of  the  second  rib,  sometimes  into  the  cartilages  of  the 
sixth  rib. 

Muscles  situated  on  the  anterior  part  of  the  Abdomen. 

They  consist  of  three  broad  layers  on  each  side  of  the  belly 
and,  of  one  layer  in  front. 
The  three  layers  are : 

28 


326 


ABDOMINAL  MUSCLES. 


1.    Obliquus  Descendens  Externus, 

Arises,  by  eight  heads,  from  the  lower  edges  of  an  equal  num- 
ber of  the  inferior  ribs,  at  a  little  distance  from  their  cartilages : 
it  always  intermixes  in  a  serrated  manner,  with  portions  of  the 

Fig.  82.* 


*  The  muscles  of  the  anterior  aspect  of  the  trunk;  on  the  left  side  the 
superficial  layer  is  seen,  and  on  the  right  the  deeper  layer.  1.  The  pecloralis 
major  muscle.  2.  The  deltoid ;  the  interval  between  these  muscles  lodges  the 
cephalic  vein.  3.  The  anterior  border  of  the  latissimus  dorsi.  4.  The  serra- 
tions of  the  serratus  magnus.  5.  The  subclavius  muscle  of  the  right  side.  6. 
The  pectoralis  minor.  7.  The  coraco-brachialis  muscle.  8.  The  upper  part  of 
the  biceps  muscle,  showing  its  two  heads.  9.  The  coracoid  process  of  the 
scapula.  10.  The  serratus  magnus  of  the  right  side.  11.  The  external  inter- 
costal muscle  of  the  fifth  intercostal  space.  12.  The  external  oblique  muscle. 
13.  Its  aponeurosis ;  the  median  line  to  the  right  of  this  number  is  the  linea 
alba  ;  the  flexuous  line  to  its  left  is  the  linea  semilunaris  ;  and  the  transverse 
lines  above  and  below  the  number,  the  lineae  transversae,  of  which  there  were 


ABDOMINAL  MUSCLES.  327 

serratus  major  anticus ;  and  generally  coheres  to  the  pectoralis 
major,  intercostals,  and  latissimus  dorsi ;  which  last  covers  the 
edge  of  a  portion  of  it  extended  from  the  last  rib  to  tKe  spine 
of  the  ilium.  — It  interdigitates  by  its  five  upper  heads  with 
the  serratus  major  anticus,  and  by  the  three  lower  with  the 
latissimus  dorsi,  where  the  latter  arises  from  the  ribs ;  a  slip 
from  the  pectoralis  covers  the  first  or  upper  head. — 

From  these  origins  the  fibres  run  obliquely  downwards  and 
forwards,  and  terminate  in  the  anterior  half  of  the  spine  of  the 
ilium,  and  in  a  tendinous  membrane,  whose  fibres  are  continued 
in  the  same  direction  until  they  meet  the  fibres  of  the  cor- 
responding tendon  of  the  other  side,  in  a  line  which  extends 
from  the  ensiform  cartilage  to  the  symphysis  pubis. 

This  line  is  called  linea  alba,  from  its  white  appearance, 
which  is  owing  to  the  connexion  of  three  tendons  with  each 
other,  without  the  intervention  of  muscles,  namely,  those  of  the 
external  and  internal  oblique,  and  the  transversalis.* 

On  each  side  of  the  line,  two  long  narrow  muscles,  (the 
recti.)  are  situated  between  these  tendons,  and  do  away  the 
white  appearance  ;  but  exterior  to  these  muscles,  the  tendons 

only  three  in  this  subject.  14.  Poupart's  ligament.  15.  The  external  abdomi- 
nal ring ;  the  margin  abovs  the  ring  is  the  superior  or  internal  pillar ;  the  mar- 
gin below  the  ring,  the  inferior  or  external  pillar;  the  curved  intercolumnar 
fibres  are  seen  proceeding  upwards  from  Poupart's  ligament  to  strengthen  the 
ring.  The  numbers  14  and  15  are  situated  upon  the  fascia  lata  of  the  thigh  ; 
the  opening  immediately  to  the  right  of  fifteen  is  the  opening  for  the  saphena 
vein.  16.  The  rectus  muscle  of  the  right  side  brought  into  view  by  the  removal 
of  the  anterior  segment  of  its  sheath :  *  the  posterior  segment  of  its  sheath 
with  the  divided  edge  of  the  anterior  segment.  17.  The  pyramidalis  muscle. 
18.  The  internal  oblique  muscle.  19.  The  conjoined  tendon  of  the  internal 
oblique  and  transversalis  descending  behind  Poupart's  ligament  to  the  pectineal 
line.  20.  The  arch  formed  between  the  lower  curved  border  of  the  internal 
oblique  muscle  and  Poupart's  ligament ;  it  is  beneath  this  arch  that  the  sper- 
matic cord  and  hernia  pass. 

*  According  to  Meckel,  the  linea  alba  performs  the  same  office  in  the  abdo- 
men as  the  sternum  does  in  the  thorax,  with  this  only  difference,  that  it  is  not 
formed  of  bone.  The  anterior  tendons  of  the  broad  muscles  are  attached  to  it, 
in  the  same  way  that  the  cartilages  of  the  ribs  are  articulated  with  the  sternum, 
and  the  difference  of  tissue  which  exists  between  it  and  the  sternum  is  attribu- 
table to  the  general  difference  of  structure  between  the  abdominal  and  pectoral 
cavities,  the  latter  being  formed  almost  entirely  of  osseous  parts,  whilst  the 
walls  of  the  former  are  fleshy  and  tendinous. — r. 


328  ABDOMINAL  MUSCLES. 

are  again  united,  and  form  a  white  line  on.  each  side,  which  is 
called  linea  semilunaris,  from  its  curved  shape. 

At  the  lower  part  of  the  tendon,  near  the  os  pabis,  the  fibred 
are  so  arranged,  that  they  form  two  bands  more  firm  and 
dense  than  the  rest  of  the  tendon,  which  are  called  columns : 
these  columns  are  separated  from  each  other ;  and  the  vacuity 
between  them  is  the  abdominal  ring,  or  aperture,  for  the 
passage  of  the  spermatic  chord  in  males  and  the  round  ligament 
of  the  uterus  in  females.  This  vacuity  or  aperture  has  an  oval 
form,  which  is  occasioned  by  some  additional  tendinous  fibres 
at  the  upper  part  of  it,  that  have  a  transverse  direction* 

The  uppermost  of  the  two  columns  is  continued  obliquely 
downwards,  and  is  inserted  into  the  os  pubis  of  the  opposite 
side,  near  the  symphysis,  decussating  the  fibres  of  the  cor- 
responding column  of  that  side. 

The  lower  edge  of  the  tendon  of  the  external  oblique  is 
attached  to  the  superior  anterior  spinous  process  of  the  ilium, 
and  is  there  blended  \yith  the  tendinous  fascia,  which  extends 
down  the  thigh. 

From  this  process  the  edge  of  the  tendon  is  extended,  like 
the  chord  of  a  bow,  across  the  concavity  formed  by  the  os 
ilium  and  os  pubis,  and  is  inserted  into  the  pubis  near  its  sym- 
physis. As  it  proceeds  from  the  spine  of  the  ilium  towards  the 
pubis,  the  edge  is  folded  inwards,  so  that  the  membrane  is 
doubled.  The  portion  which  is  turned  inwards,  (Gimbernat's 
ligament,)  is  very  small  at  its  commencement,  and  continues 
so  for  a  great  part  of  its  extent ;  but  becomes  much  broader 
within  an  inch  of  its  termination.  This  broad  extremity  is 
inserted  into  the  small  process  of  the  pubis  near  the  sym- 
physis, and  into  a  ridge  which  continues  backward  from  the 
process  to  the  brim  of  the  pelvis,  so  that  the  tendinous  mem- 
brane at  this  part  is  doubled  ;  the  part  which  is  turned  back 
being  about  an  inch  broad  at  the  place  of  its  insertion  into  the 
pubis. 

This  doubling  forms  a  partial  sheath  near  the  pubis  for  con- 
taining the  spermatic  chord,  and  supports  it  for  a  short  distance 
on  the  inside  of  the  abdominal  ring. 


ABDOMINAL  MUSCLES.  329 

The  edge  formed  by  the  fold  of  the  membrane  is  called 
Poupart's  ligament,  and  is  very  firm  and  strong ;  owing  to 
the  membrane  being  thicker  at  that  place.  The  real  ^dge,  or 
termination  of  the  portion  which  is  folded  inwards,  is  arranged 
in  the  following  manner :  the  part  which  is  nearest  to  the  spine 
of  the  ilium  is  continued  into  the  cellular  membrane,  or  the 
fascia,  which  is  between  the  internal  oblique  and  transversalis 
muscles,  and  the  iliacus  internus. 

But  the  edge  of  that  part  of  Poupart's  ligament  which  is 
inserted  into  the  ridge  of  the  pubis  seems  to  form  a  portion  of 
an  oval  opening,  which  is  occupied  in  part,  but  not  completely, 
by  the  crural  vessels. 

— The  femoral  artery  is  found  at  the  outer  margin  of  this  oval 
opening,  see  fig.  82.  The  femoral  vein  is  placed  on  the  inner 
side  of  the  artery  ;  on  the  inner  side  of  the  vein  again  is  left  a 
roundish  opening,  the  proper  crural  ring,  occupied  only  by  some 
loose  fat,  lymphatic  vessels  and  a  small  gland,  through  which 
the  viscera  protrude  in  crural  hernia. — 

— This  edge  of  Poupart's  ligament,  inserted  into  the  ridge  or 
crest  of  the  pubis  is  of  a  triangular  shape,  and  is  called  Gim- 
bernai's  ligament.  It  is  one  of  the  seats  of  stricture  in  crural 
hernia.  The  base  of  the  triangle  is  towards  the  syrnphysis 
pubis. — 

A  portion  of  the  fascia  lata  of  the  thigh,  which  covers  these 
vessels,  passes  under  this  portion  of  the  tendon,  and  is  also 
inserted  into  the  ridge  of  the  pubis  ;  so  that  when  the  intestines 
protrude  at  this  aperture,  and  are  strangulated,  this  portion  of 
the  fascia  of  the  thigh  must  also  compress  them.  — This 
portion  of  the  fascia  lata  femoris,  is  called  the  crescentic  or 
falciform  portion  of  the  fascia  lata.  The  sharp  edge  at  its 
inner  part,  by  which  it  is  nearly  continuous  with  Gimbernat's 
ligament,  and  which  is  directed  downwards  and  backwards,  is 
called  Key's  ligament  or  the  femoral  ligament;  it  is  directly 
above  or  in  front  of  the  crural  ring — that  space  between  the 
crural  vein  and  Gimbernat's  ligament,  included  in  the  sheath 
of  the  femoral  vessels,  and  through  which  the  viscera  protrude 
in  crural  hernia. — 

28* 


330  ABDOMINAL  MUSCLES. 

The  fascia  lata  of  the  thigh  is  connected  with  the  external 
or  lower  edge  of  Poupart's  ligament,  in  its  whole  extent :  this 
is  called  the  sartorial  portion. 

— The  fascia  lata  may  here  be  considered  as  divided  into  two 
layers  :  1st,  The  sartorial.  2d,  The  pectineal  which  contin- 
uous above  and  without,  as  seen  in  fig.  83,  is  reflected  behind 

Fig*83* 


llie  sheath  of  the  vessels,  and  over  the  anterior  surface  of  the 
pectineus  muscle  up  to  the  spine  of  the  pubis.  The  sheath  of 
the  femoral  vessels  is  formed  by  an  extension  downwards  of 
the  fascia  transversalis  and  fascia  iliaca  for  about  an  inch  and 
a  half  between  these  layers  of  the  fascia  lata.-— And  there  is 

*  A  section  of  the  structures  which  pass  beneath  the  femoral  arch.  1.  Pou- 
part's  ligament.  2,  2.  The  upper  or  sartorial  portion  of  the  fascia  lata,  attached 
along  the  margin  of  the  crest  of  the  ilium,  and  along  Ponpart's  ligament,  as  far 
as  the  spine  of  the  os  pubis  (3).  4.  The  pubic  or  pectineal  portion  of  the  fascia 
lata,  continuous  at  3  with  the  iliac  portion,  and  passing  outwards  behind  the 
sheath  of  the  femoral  vessels  to  its  outer  border  at  5,  where  it  divides  into  two 
layers ;  one  is  continuous  with  the  sheath  of  the  psoas  (6)  and  iliacus  (7) ;  the 
other  (8)  is  lost  upon  the  capsule  of  the  hip-joint  (9).  10.  The  femoral  nerve, 
enclosed  in  the  sheath  of  the  psoas  and  iliacus.  11.  Gimbernat's  ligament. 
12.  The  femoral  ring,  within  the  femoral  sheath.  13.  The  femoral  vein.  14. 
The  femoral  artery  :  the  two  vessels  and  the  ring  are  surrounded  by  the  femo- 
ral sheath,  and  thin  septa  are  sent  between  the  anterior  and  posterior  wall  of 
the  sheath,  dividing  the  artery  from  the  vein,  and  the  vein  from  the  femoral 
ting. 


ABDOMINAL  MUSCLES.  331 

also  a  fascia  (fascia  superficialis  abdominis)  which  covers  the 
whole  tendon  of  the  external  oblique  muscle,  and  passes  from  it 
down  upon  the  fascia  of  the  thigh  :  which  also  connects  the 
tendon  of  the  external  oblique  to  the  fascia  of  the  thigh,  and 
serves  to  bind  it  down.  From  these  connexions  it  is  probable 
that  the  tendon  is  in  a  very  different  situation  before  dissection, 
from  what  it  is  afterwards  ;  as  the  division  of  these  connexions, 
necessarily  made  by  the  dissection,  renders  it  much  more  loose 
than  it  could  have  been  while  the  parts  were  undivided.  This 
structure  has  latterly  been  called  the  crural  arch.  The  fascia 
which  covers  the  tendon  of  the  external  oblique  muscle,  and 
descends  upon  the  thigh,  can  be  examined  very  easily  in  anasar- 
cous  subjects ;  as  in  them,  the  cellular  membrane,  which  is 
situated  between  this  fascia  and  the  tendon,  is  somewhat  dis- 
tended by  the  effused  fluid. 

To  prepare  Poupart's  ligament  or  the  crural  arch,  for  exami- 
nation, remove  carefully  the  cellular  membrane  from  the  tendon 
of  the  external  oblique,  and  also  from  the  fascia  of  the  thigh, 
taking  care  not  to  remove  any  part  of  the  fascia  which  passes 
under  the  tendon  to  be  inserted  into  the  os  pubis.  Then  make 
an  incision  in  the  tendon  of  the  external  oblique,  about  three 
inches  above  Poupart's  ligament,  parallel  to  it,  and  nearly  of 
the  same  length  ;  make  a  second  incision  from  the  upper  end 
of  this,  to  the  junction  of  the  aforesaid  ligament  with  the  supe- 
rior anterior  spine  of  the  ilium  ;  and  a  third  incision  from  the 
lower  end  to  the  abdominal  ring.  Dissect  this  flap  carefully 
from  the  internal  oblique,  until  the  spermatic  chord,  the  cre- 
master  muscle,  and  the  lower  origin  of  the  internal  oblique, 
are  perfectly  uncovered.  After  examining  the  internal  surface 
of  the  tendon  and  its  insertion  at  the  pubis,  the  fascia  of  the 
thigh  may  be  dissected,  so  that  its  connexion  with  the  folded 
edge  of  the  tendon,  and  its  insertion  into  the  pubis,  may  also  be 
examined. 

The  external  oblique  muscles  compress  the  abdomen,  and 
therefore  contribute  to  the  evacuation  of  its  contents  :  if  the 
diaphragm  is  in  a  passive  state,  they  force  it  upwards,  by 
pressing  the  abdominal  viscera  against  it ;  and  thus  assist  in 


332  ABDOMINAL  MUSCLES. 

producing  expiration  and  its  various  modifications  of  coughing, 
sneezing,  &c. 

They  bend  the  spine  forwards,  or  approach  the  thorax  to  the 
pelvis. 

When    one  acts  separately,  it  bends  the  trunk  obliquely  to 

the  side  on  which  it  is  situated. 

• 
3.    Obliquus  Ascendens  Inter  nus, 

Arises  from  the  spine  of  the  ilium  the  whole  length  between 
the  posterior  and  superior  anterior  spinous  process ;  from  the 
os  sacrum  and  the  three  undermost  lumbar  vertebrae,  by  a 
tendon,  (fascia  lumborum)  common  to  it,  to  the  serratus 
posticus  inferior  muscle,  and  to  the  latissimus  dorsi ;  from 
Poupart's  ligament,  at  the  middle  of  which  it  sends  off  the 
beginning  of  the  cremaster  muscle  ;  the  spermatic  chord  in  the 
male,  or  round  ligament  of  the  womb  in  the  female,  passes 
under  its  thin  edge,  with  the  exception  of  a  few  detached 
fibres. 

Inserted  into  the  cartilago-ensiformis,  into  the  cartilages  of 
the  seventh,  and  those  of  the  false  ribs  ;  but,  at  the  upper  part, 
it  is  extremely  thin,  resembling  a  cellular  membrane,  and  only 
becomes  fleshy  at  the  cartilage  of  the  tenth  rib.  Here  its 
tendon  divides  into  two  layers ;  the  anterior  layer,  with  a  great 
portion  of  the  inferior  part  of  the  posterior  layer,  joins  the 
tendon  of  the  external  oblique,  and  runs  over  the  rectus  to  be 
inserted  into  the  whole  length  of  the  linea  alba.  The  posterior 
layer  joins  the  tendon  of  the  transversalis  muscle  as  low  as 
half  way  between  the  umbilicus  and  os  pubis  ;  but,  below  this 
place,  only  a  few  fibres  of  the  posterior  layer  are  seen,  and  the 
rest  of  it  passes  before  the  rectus  muscle,  and  is  inserted  into 
the  linea  alba  ;  so  that  the  whole  tendon  of  the  external 
oblique  muscle,  with  the  anterior  layer  of  the  internal  oblique, 
passes  before  the  rectus  muscle ;  and  the  whole  posterior 
layer  of  the  internal  oblique,  together  with  the  whole  tendon 
of  the  transversalis  muscle,  excepting  at  the  inferior  part, 
passes  behind  the  rectus,  and  is  inserted  into  the  linea  alba. 
At  its  undermost  part,  it  is  inserted  into  the  forepart  of  the  os 
pubis. 


ABDOMINAL  MUSCLES.  333 

Use.     To  assist  the  former ;  but  it  bends  the  trunk  in  the 
reverse  direction. 

Fig.  84.* 


3.  Transversalis, 

Arises,  tendinous,  but  soon  becoming  fleshy,  from  the  inner 
or  back  part  of  the  cartilages  of  the  seven  lower  ribs,  where 
some  of  its  fibres  are  continued  with  those  of  the  diaphragm 
and  the  intercostal  muscles  ;  by  a  broad  thin  tendon,  connected 
to  the  transverse  processes  of  the  last  vertebra  of  the  back,  and 
the  four  superior  vertebrae  of  the  loins  ;  fleshy,  from  the  whole 
spine  of  the  os  ilium  internally,  and  from  the  tendon  of  the 
external  oblique  muscle  where  it  intermixes  with  some  fibres 
of  the  internal  oblique. 

Inserted  into  the  cartilago-ensiformis,  and  into  the  whole 
length  of  the  linea  alba,  excepting  its  lowermost  part. 

Use.    To  support  and  compress  the  abdominal  viscera,  and 

*  Transverse  section  of  abdomen. — a,  Division  of  the  tendon  of  the  internal 
oblique  into  two  layers,  forming  a  sheath  in  which  is  contained  the  rectus  muscle 
b,  External  oblique,  r,  Internal  oblique,  d.  Transversalis.  et  Between  the 
last  rib  and  the  crista  of  the  ilia,  the  fibres  of  the  transversalis,  arise  from  a 
tendinous  layer,  which  is  trifoliate  in  its  origin,  according  to  Todd.  /,  The 
anterior  division,  arising  from  the  roots  of  the  transverse  processes,  and  cover- 
ing the  quadratus  lumborum  muscle,  h,  g,  The  middle,  which  is  weak,  attached 
to  the  apices  of  the  transverse  processes.  The  posterior  is  the  fascia  lum 
borum. 


334 


ABDOMINAL  MUSCLES. 


Fig.  85.*  it  is  so  particularly  well  adapted 

for  the  latter  purpose,  that  it 
might  be  called  the  proper  con- 
strictor of  the  abdomen. 

The  long  muscle  in  the  middle 

is  named 

• 

Rectus  AbdominiSj 

Arises,  by  two  heads,  from  the 
ligament  of  the  cartilage  which 
joins  the  two  ossa  pubis  to  each 
other;  runs  upwards  the  whole 
length  of,  and  parallel  to  the  linea 
alba,  growing  broader  and  thin- 
ner as  it  ascends. 

Inserted  into  the  cartilages  of 
the  three  inferior  true  ribs,  and 
often  intermixed  with  some  fibres 
of  the  pectoral  muscle. 

It  is  generally  divided  by  three 
tendinous  intersections :  the  first  is  at  the  umbilicus ;  the 
second,  where  it  runs  over  the  cartilage  of  the  seventh  rib  ; 
and  the  third  in  the  middle  between  these ;  and  there  is 
commonly  a  half  intersection  below  the  umbilicus.  These 
intersections  (linea  transversce)  seldom  penetrate  through 
the  whole  thickness  of  the  muscle  :  they  adhere  firmly  to  the 


*  A  lateral  view  of  the  trunk  of 'the  body,  showing  its  muscles,  and  particu- 
larly the  transversalis  abdominis.  ] .  The  costal  origin  of  the  lattissimus  dorsi 
muscle.  2.  The  serratus  magnus.  3.  The  upper  part  of  the  external  oblique 
muscle  divided  in  the  direction  best  calculated  to  show  the  muscles  beneath 
without  interfering  with  its  indigitations  with  the  serratus  magnus.  4.  Two  of 
the  external  intercostal  muscles.  5.  Two  of  the  internal  intercostals.  6.  The 
transversalis  muscle.  7.  Its  posterior  aponeurosis.  8.  Its  anterior  aponeurosis 
forming  the  most  posterior  layer  of  the  sheath  of  the  rectus.  9.  The  lower  part 
of  the  left  rectus  with  the  aponeurosis  of  the  transversalis  passing  in  front. 
10.  The  right  rectus  muscle.  11.  The  arched  opening  left  between  the. lower 
border  of  the  transversalis  muscle  and  Poupart's  ligament,  through  which  the 
spermatic  cord  and  hernia  pass.  12.  The  gluteus  maximus,  and  medius,  and 
tensor  vaginae  femoris  muscles  invested  by  fascia  lata. 


ABDOMINAL  MUSCLES.  335 

anterior  part  of  the  sheath,  but  very  slightly  to  the  posterior 
layer.* 

Use.  To  compress  the  forepart,  but  more  particularly  the 
lower  part  of  the  belly ;  to  bend  the  trunk  forwards,  or  to  raise 
the  pelvis.  By  its  tendinous  intersection,  it  is  enabled  to  con- 
tract at  any  of  the  intermediate  spaces ;  and,  by  its  connexion 
with  the  tendons  of  the  other  muscles,  it  is  prevented  from 
changing  place,  and  from  rising  into  a  prominent  form  when 
in  action. 

The  short  muscle  in  the  middle  is  named 

Pyramidatis, 

Arises  along  with  the  rectus  ;  and  running  upwards  within 
the  same  sheath,  is 

Inserted,  by  an  acute  termination,  near  half  way  between 
the  os  pubis  and  umbilicus,  into  the  linea  alba  and  inner  edge 
of  the  rectus  muscle. 

As  it  is  frequently  wanting  in  both  sides  without  any  incon- 
venience, its 

Use  seems  to  be,  to  assist  the  inferior  part  of  the  rectus. 

Muscles  about  the  male  Organs  of  Generation. 

The  testicles  are  said  to  have  a  thin  muscle  common  to  both, 
and  one  proper  to  each. 

The  common  muscle  is  called  the 


Dartos. 

This  consists  of  muscular  fibres  blended  with   the  cellular 
membrane   lining   the  scrotum ;    and   therefore  this   portion  of 

*  To  obtain  an  accurate  idea  of  the  arrangement  of  the  tendons  of  the  three 
large  pair  of  abdominal  muscles,  it  will  be  necessary  to  raise  or  separate  the 
external  oblique  muscle  and  tendon  from  the  internal  oblique  and  its  tendon,  as 
far  as  the  linea  semilunaris,  and  to  separate  the  internal  oblique  in  the  same 
manner  from  the  transversalis ;  and  then  to  make  an  incision  in  the  tendon  of 
the  external  oblique  parallel  to  the  linea  alba,  and  about  an  inch  and  a  half 
from  it,  so  as  to  bring  the  whole  of  the  rectus  muscle  into  view.  The  structure 
of  the  sheath  which  contains  the  rectus  can  then  be  examined. 


336  PERINEAL  MUSCLES. 

skin  is  capable  of  being  corrugated  and  relaxed  in  a  greater 
degree  than  the  skin  in  other  places. 

The  muscle  proper  to  each  testicle  is  the 

Cremaster. 

Arises  from  the  internal  oblique,  where  a  few  fibres  of  that 
muscle  intermix  with  the  tran^versalis,  near  the  juncture  of  the 
os  ilium  and  pubis,  over  which  part  it  passes,  after  having 
pierced  the  ring  of  the  externus  obliquus  ;  and  then  it  descends 
upon  the  spermatic  chord. 

Inserted  into  the  tunica  vaginalis  of  the  testicle,  upon  which 
it  spreads,  and  is  insensibly  lost.* 

Use.  To  suspend  and  draw  up  the  testicle,  and  to  compress 
it  in  the  act  of  coition. 

The  penis  has  three  pairs  of  muscles : 

1.    Erector  Penis. 

Arises,  tendinous  and  fleshy,  from  the  tuberosity  of  the  os 
ischium,  and  runs  upwards,  embracing  the  whole  crus  of  the 
penis 

Inserted  into  the  strong  tendinous  membrane  that  covers  the 
corpus  cavernosum  penis,  nearly  as  far  as  the  union  of  these 
bodies. 

Use.  To  compress  the  crura  penis,  by  which  the  blood  is 
pushed  from  it  into  the  forepart  of  the  corpora  cavernosa  ;  and 

*  M.  J.  Cloquet  says,  that  the  scattered  fasciculi  of  this  muscle  are  collected 
after  their  distribution  on  the  tuniea  vaginalis,  and  run  up  on  the  inner  side  of 
the  chord,  to  be  inserted  into  the  spine  of  the  pubis.  He  makes  the  inference 
from  this,  that  the  cremaster  is  a  kind  of  muscular  loop,  drawn  down  by  the 
descent  of  the  testicle.  I  am  satisfied  that  the  muscle  in  robust  subjects,  fre- 
quently exists,  more  or  less,  after  the  manner  in  which  he  speaks  of  it :  but,  in 
the  emaciated,  it  is  very  indistinct,  as  regards  such  an  insertion.  In  the  cases 
where  I  have  seen  this  insertion  into  the  spine  of  the  pubis,  the  quantity  of 
muscular  fibre  has  been  by  no  means  so  great  there  as  at  its  origin.  This  ob- 
servation of  M.  Cloquet's  is  ingenious  and  interesting,  but  it  is  well  worthy  of 
consideration,  that  Mr.  John  Hunter's  opinion,  in  his  paper  on  the  descent  of 
the  testicle,  is  opposed  to  it,  and  on  the  following  grounds  :  in  the  young  ram, 
and  in  several  other  animals,  the  cremaster  muscle  is  formed  before  the  testicle 
descends  from  the  abdomen  into  the  scrotum,  being  reflected  along  the  guber- 
naculum  testis  upwards  towards  the  loins.  Mr.  Hunter  could  not,  it  is  true, 
verify  the  same  observation  on  the  human  subject,  but  he  is  disposed,  from 
analogy,  to  believe  that  something  of  the  kind  exists. — H. 


PERINEAL  MUSCLES, 


337 


the  penis  is  by  that  means  more  Fig.  86.* 

completely  distended.  The  erec- 
tores  seem,  likewise,  to  keep  the 
penis  in  its  proper  direction. 

2.  Accelerator  Urince  seu  Ejac- 
ulator  Seminis. 

Arises,  fleshy,  from  the  sphinc- 
ter ani  and  membranous  part  of 
the  urethra  ;  and  tendinous,  from 
the  crus,  nearly  as  far  forwards 
as  the  beginning  of  the  corpus 
cavernosum  penis :  the  inferior 
fibres  run  more  transversely  ;  and 
the  superior  descend  in  an  ob- 
lique direction. 

Inserted  into  a  line  in  the  middle  of  the  bulb  where  it  joins 
with  its  fellow,  by  which  the  bulb  is  completely  enclosed. 

Use.  To  drive  the  urine  or  semen  forwards  ;  and,  by  grasping 
the  bulb  of  the  urethra,  to  push  the  blood  towards  the  corpus 
cavernosum  and  the  glans,  by  which  these  parts  are  distended. 

3.   Transversus  Perinei, 

Arises  from  the  tough  fatty  membrane  that  covers  the  tube- 
rosity  of  the  os  ischium  ;  from  thence  it  runs  transversely 
inwards,  and  is 

*  Cremaster,  from  Sir  A,  Cooper's  work.  0,  Rectus  muscle,  b,  Descending 
portion  of  the  fascia  superticialis.  c,  The  internal  oblique,  d.  Conjoined  ten- 
dons, e,  The  descending  fibres  of  oblique.  /,  Point  of  insertion  into  the  pubis. 
g,  Ascending  fibres,  h,  One  of  the  reversed  arches. 

The  formation  of  the  cremaster,  appears  to  be  completed  by  the  testicle  in 
its  descent,  as  Scarpa,  Cloquet,  Cooper,  Velpeau,  and  Todd  admit.  Prior  to 
the  descent,  the  gubernaculnm  testis  occupies  the  inguinal  canal,  and  is  covered 
by  the  fibres  of  the  cremaster  which  divide  inferiorly  into  three  processes  ac- 
cording to  Mr.  Curling. — The  outer  process  which  is  the  largest  running  to  be 
inserted  on  Poupart's  ligament,  the  middle  one  to  the  bottom  of  the  scrotum, 
where  it  joins  the  dartos,  the  internal  one  to  the  os  pubis  and  the  sheath  of  the 
rectus  muscle.  The  testis  is  drawn  down  by  the  successive  action  of  these 
muscular  bands  of  the  gubernaculum,  the  testis  as  stated  by  Mr.  Curling  is 
drawn  first  into  the  inguinal  canal,  then  through  the  external  abdominal  ring. 
and  finally  down  into  the  bottom  of  the  scrotal  pouch,  the  fibres  of  the  cremas- 
ter remaining  subsequently  as  a  muscular  envelop  surrounding  the  g'and  and 
the  front  of  the  cord. 

29 


338  MUSCLES  OF    THE  ANUS. 

Inserted  into  the  accelerator  urinae,  and  into  that  part  of  the 
sphincter  ani  which  covers  the  bulb.  The  place  of  junction  of 
these  muscles  is  called  the  perineal  point  or  centre. 

Use.  To  dilate  the  bulb,  and  draw  the  perineum  and  verge  of 
the  anus  a  little  outwards  and  backwards. 

There  is  often  a  fourth  muscle,  named 

• 

Transversus  Perinei  Alter, 

Arises  behind  the  former,  runs  more  obliquely  forwards,  and  is 
Inserted  into  that  part  of  the  accelerator  urinae  which  covers 
the  anterior  part  of  the  bulb  of  the  urethra. 
Use.   To  assist  the  former. 


In  the  Medico-Chirurgical  Transactions,  James  Wilson,  Esq.  F.  R.  S.  gives 
the  following  account  of  two  small  muscles  of  the  membranous  part  of  the 
urethra,  viz:  Each  muscle  has  a  tendon  which,  at  first,  is  round,  but  soon  be- 
comes flattened  as  it  descends.  It  is  affixed  to  the  back  part  of  the  symphysis 
pubis,  about  one-eighth  of  an  inch  above  the  lower  edge  of  the  cartilaginous 
arch  of  the  pubes,  and  nearly  at  the  same  distance,  below  the  attachment  of  the 
tendon  of  the  bladder :  to  which,  and  to  the  tendon  of  the  corresponding  muscle, 
it  is  connected  by  very  loose  cellular  membrane.  The  tendon  descends  at  first 
in  contact  with,  and  parallel  to,  its  fellow  :  it  soon  becomes  broader,  and  sends 
off  fleshy  fibres,  which  also  increase  in  breadth,  and,  when  near  the  upper  sur- 
face of  the  membranous  part  of  the  urethra,  separate  from  those  of  the  opposite 
side,  spread  themselves  on  the  side  of  the  membranous  part  of  the  urethra 
through  its  whole  extent ;  then  fold  themselves  under  it,  and  meet  in  a  middle 
tendinous  line  with  similar  fibres  of  the  opposite  side. 

Its  action  seems  to  be  to  draw  up  the  membranous  part  of  the  urethra,  and 
compress  it  against  the  inside  of  the  cartilaginous  arch  of  the  pubes  ;  and  also 
to  contract  the  circle  round  the  membranous  portion,  so  as  to  diminish  and  even 
close  up  the  passage  of  the  urine.*  It  is  known  under  the  name  of  the  muscle 
of  Wilson  .f 


*  I  have  frequently  dissected  for  this  muscle,  and  in  only  two  or  three  cases  have  been 
able  to  satisfy  myself  of  its  having  an  existence  distinct  from  that  of  the  Levator  Ani.  My 
friend,  Mr.  Shaw,  who  occupies  a  distinguished  rank  among  the  cultivators  of  anatomy  in 
London,  admits  of  this  muscle,  but  says  there  is  much  difficulty  in  distinguishing  it  from  the 
ligament  of  the  urethra,  meaning,  I  presume,  its  triangular  ligament.— H. 

f  The  vertical  muscular  fibres  discovered  by  Mr.  Wilson  and  a  transverse  band  connected 
•with  it,  described  by  Mr.  Guthrie,  and  both  together  commonly  considered  now  as  forming 
the  proper  compressor  urethra  muscle.— From  repeated  examination,  I  have  no  doubt  of 
their  being  properly  entitled  to  this  name. — The  muscle  of  Guthrie  arises  by  a  tendinous 
point  from  the  ranus  of  the  Ischium  and  passing  transversely  inwards,  splits  into  two  layers 
which  by  junction  with  its  fellow  of  the  opposite  side,  embrace  the  upper  and  lower  surface 
of  the  membranous  portion  of  the  urethrae  from  the  bulb  to  which  it  is  connected  as  front 
to  the  point  of  the  mastale  to  which  it  is  attached  behind.— p. 


MCSCLES  OF    THE  ANUS.  339 

Muscles  of  the  Anus. 

The  anus  has  a  single  muscle,  and  one  pair. 
The  single  muscle  is 

Sphincter   Ani. 

Arises  from  the  skin  and  fat  that  surrounds  the  verge  of  the 
anus  on  both  sides,  nearly  as  far  as  the  tuber  of  the  os  ischium ; 
the  fibres  are  gradually  collected  into  an  oval  form,  and  surround 
the  extremity  of  the  rectum. 

Fig.  81* 


Inserted,  before,  by  a  narrow  point,  into  the  perineum,  accel- 
eratores  urinae,  and  transversi  perinei ;  behind,  by  an  acute  ter- 
mination, into  the  extremity  of  the  os  coccygis. 

Use.  Shuts  the  passage  through  the  anus  into  the  rectum  ; 
pulls  down  the  bulb  of  the  urethra,  by  which  it  assists  in  ejecting 
the  urine  and  semen.  — The  sphincter  ani  is  always  in  a  con- 
tracted state,  except  at  the  time  of  the  evacuation  of  the  faeces. 
When  the  sphincter  is  in  a  healthy  state,  it  may  by  made  by  an  effort 
of  the  will  to  contract  more  strongly,  but  it  cannot  be  made  to  relax. 

*  The  muscles  of  the  perineum.  1.  The  acceleratores  urinae  muscles  ;  the 
figure  rests  upon  the  corpus  spongiosum  penis.  2.  The  corpus  cavernosum  of 
one  side.  3.  The  erector  penis  of  one  side.  4.  The  transversus  perinei  of  one 
side.  5.  The  triangular  space  through  which  the  deep  perineal  fascia  is  seen. 
6.  The  sphincter  ani ;  its  anterior  extremity  is  cut  off.  7.  The  levator  ani  of 
the  left  side ;  the  deep  space  between  the  tuberosity  of  the  ischium  (8)  and  the 
anus,  is  the  ischio-rectal  fossa  ;  the  same  fossa  is  seen  upon  the  opposite  side. 
9.  The  spine  of  the  ischium.  10.  The  left  coccygeus  muscle.  The  boundaries 
of  the  perineum  are  well  seen  in  this  engraving. 


340  MUSCLES  OF    THE  ANUS. 

— The  irritation  induced  by  the  accumulation  of  faeces  in  the 
rectum,  causes  it  at  first  to  contract  more  strongly,  and  the 
contraction  continues  till  it  is  overcome,  by  the  increasing 
effort  of  the  muscular  fibres  of  the  rectum,  and  the  action  of 
the  diaphragm  and  abdominal  muscles.  It  acts  also  as  an  anta- 
gonist to  the  levator  ani  muscles. — 

-V.  B.  The  sphincter  interhus  of  Albinus  and  Douglas,  is 
only  that  part  of  the  cellular  fibres  of  the  muscular  coat  of  the 
rectum  which  surrounds  its  extremity. 

Levator  Ani: 

Arises  from  the  os  pubis  within  the  pelvis,  as  far  up  as  the 
upper  edge  of  the  foramen  thyroideum,  and  joining  of  the 
os  pubis  with  the  os  ischium  ;  from  the  thin  tendinous  mem- 
brane that  covers  the  obturator  internus  and  coccygeus  muscle, 
and  from  the  spinous  process  of  the  os  ischium  :  its  fibres  run 
down  like  rays  from  a  circumference  to  a  centre. 

Inserted  into  the  sphincter  ani,  acceleratores  urinse,  and  anterior 
part  of  the  two  last  bones  of  the  os  coccygis ;  surrounds  the 
extremity  of  the  rectum,  neck  of  the  bladder,  prostate  gland,  and 
part  of  the  vesicula  seminalis ;  so  that  its  fibres  behind  and 
below  the  os  coccygis  joining  it  with  its  fellow,  they  together 
very  much  resemble  the  shape  of  a  funnel. 

Use.  To  draw  the  rectum  upwards  after  the  evacuation  of 
the  fasces,  and  to  assist  in  shutting  it ;  to  sustain  the  contents  of 
the  pelvis,  and  to  help  in  ejecting  the  semen,  urine,  and  contents 
of  the  rectum  ;  and,  perhaps  by  pressing  upon  the  veins,  to 
contribute  greatly  to  the  erection  of  the  penis. 

— The  muscular  funnel,  formed  by  the  levator  ani  muscles  of 
the  two  sides  is  antagonized  by  the  action  of  the  sphincter  ani, 
which,  by  its  connexion  with  the  coccyx  and  perineal  centre 
prevents  its  lower  extremity  from  being  drawn  upwards. 
— When  the  sphincter  is  inflamed,  and  a  fluid  effused  among  its 
fibres,  as  is  an  occasional  occurrence  in  the  bowel  complaint  of 
children,  the  sphincter  loses  its  power,  and  the  levator  ani  muscles, 
unopposed,  retract ;  and  thus  by  everting  the  lower  margin  of  the 
rectum,  contribute  mainly  to  the  formation  of  prolapsus  ani. — 


PERINEAL  MUSCLES  OF  THE  FEMALE.          341 

Muscles  of  the  Female  Organs  of  Generation. 

The  clitoris  has  one  pair. 

y 
Erector   Clitoridis, 

Arises  from  the  crus  of  the  os  ischium  internally,  and  in  its 
ascent  covers  the  crus  of  the  clitoris  as  far  up  as  the  os  pubis. 

Inserted  into  the  upper  part  of  the  crus  and  body  of  the 
clitoris. 

Use.  Draws  the  clitoris  downwards  and  backwards ;  and 
may  serve  to  make  the  body  of  the  clitoris  more  tense  by 
squeezing  the  blood  into  it  from  its  crus. 

The  vagina  has  one  pair. 

Sphincter  Vagina, 

Arises  from  the  sphincter  ani,  and  from  the  posterior  side  of 
the  vagina,  near  the  perineum ;  from  thence  it  runs  up  the 
side  of  the  vagina,  near  its  external  orifice,  opposite  to  the 
nymphcE  and  covers  the  corpus  cavernosum  vaginae. 

Inserted  into  the  crus  and  body  or  union  of  the  crura 
clitoridis. 

Use.  Contracts  the  mouth  of  the  vagina,  and  compresses  its 
vascular  plexus,  called  corpus  cavernosum,  or  rete  mirabik. 

Transversus  Perinei, 

Arises,  as  in  the  male,  from  the  fatty  cellular  membrane  which 
covers  the  tuberosity  of  the  os  ischium. 

Inserted  into  the  upper  part  of  the  sphincter  ani,  and  into  a 
white  hardish  tough  substance  in  the  perineum,  between  the 
lower  part  of  the  pudendum  and  anus. 

Use.    To  sustain  and  keep  the  perineum  in  its  proper  place. 

The  anus,  as  in  the  male,  has  a  single  muscle,  and  one  pair. 

Sphincter  Ani. 

Arises,  as  in  the  male,  from  the  skin  and  fat  surrounding  the 
extremity  of  the  rectum. 

Inserted,  above,  in  the  white  tough  substance  of  the  perineum 
(jpcrincal  centre  ;)  and  below,  into  the  point  of  the  os  coccygis. 

Use.   To  shut  the  passage  into  the  rectum ;  and,  by  pulling 


342 


MUSCLES  OF    THE  ABDOMINAL  CAVITY. 


down  the   perineum,  to  assist  in   contracting  the  mouth  of  the 


Levator  Ani, 

Arises,  as  in  the  male,  within  the  pelvis,  and  descends  along 
the  inferior  part  of  the  vagina  and  rectum. 

Inserted  into  the  perineum^  sphincter  ani,  extremity  of  the 
vagina  and  rectum. 

Use.  To  raise  the  extremity  of  the  rectum  upwards,  to 
contract  the  inferior  part  of  the  rectum,  and  to  assist  in  con- 
tracting and  supporting  the  vagina  ;  and,  perhaps,  by  pressing 
on  the  veins,  to  contribute  to  the  distention  of  the  cells  of  the 
clitoris  and  corpus  cavernosum  of  the  vagina. 

Muscles  situated  within  the  Cavity  of  the  Abdomen. 


Fig.  88.* 


These  consist  of  a  single 
muscle,  and  four  pair. 

Diaphragma. 
This  broad  thin  muscle, 
"     which   makes    a   complete 
septum   between   the   tho- 
c     rax  and  abdomen,  is  con- 
cave   below    and    convex 
above  ;  the  middle  of  it  on 
each  side  reaching  as  high 
within   the   thorax   of  the 
skeleton  as  the  fourth  rib : 
it     is    commonly    divided 
into  two  portions. 
1.    The  superior  or, 

Greater  Muscle  of  the  Dia- 
phragm. 
Arises,  by  distinct  fleshy 

*  Thorax  of  a  male.— On  the  left  side  the  muscles  are  removed  ;  on  the  right 
ihey  are  left  in  situ,  a,  a,  Cervical  and  lumbar  parts  of  the  spinal  column,  the 
dorsal  portion  is  concealed  by  the  sternum,  b.  c,  c,  The  true  ribs,  c',  The  false 
ribs,  d,  The  clavicle,  e,  Intercostal  muscles.  /,  Last  false  rib,  concealed  by 
the  origin  of  a  part  of  the  greater  muscle  of  the  diaphragm,  g,  The  arch 


MUSCLES  OF    THE   ABDOMINAL  CAVITY.  343 

fibres,  from  the  cartilago-ensiformis,  from  the  cartilages  of  the 
seventh,  and  of  all  the  inferior  ribs  on  both  sides.  The  fibres 
from  the  cartilago-ensiformis,  and  from  the  seventh  and  eighth 
ribs,  run  obliquely  upwards  and  backwards ;  from  the  ninth  and 
tenth,  transversely  inwards  and  upwards,  and  from  the  eleventh 
and  twelfth,  obliquely  upwards.  From  these  different  origins 
the  fibres  run,  like  radii  from  the  circumference  to  the  centre  of 
a  circle  ;  and  are 

Inserted  into  a  cordiform  tendon,  of  a  considerable  breadth, 
which  is  situated  in  the  middle  of  the  diaphragm,  and  in  which, 
therefore,  the  fibres  from  opposite  sides  are  interlaced.  To- 
wards the  right  side  the  tendon  is  perforated,  by  a  triangular 
hole,  for  the  passage  of  the  vena  cava  inferior  ;  and  to  the 
upper  convex  part  of  it  the  pericardium  and  mediastinum  are 
connected. 

The  inferior,  lesser  muscle,  or 

Appendix  of  the  Diaphragm, 

Arises  from  the  second,  third  and  fourth  lumbar  vertebrae,  by 
eight  heads,  of  which,  two  in  the  middle,  commonly  called  its 
crura  are  the  longest,  and  begin  tendinous.  Between  the  crura, 
the  aorta  and  thoracic  duct  pass  ;  and  on  the  outside  of  these, 
the  great  sympathetic  nerves  and  branches  of  the  vena  azygos 
perforate  the  shorter  heads.  The  muscular  fibres  run  obliquely 
upwards  and  forwards,  and  form  in  the  middle  two  fleshy  col- 
umns, which  decussate  and  leave  an  oval  space  between  them 
for  the  passage  of  the  oesophagus  and  eighth  pair  of  nerves. 
Two  bow  shaped  ligaments  are  formed  on  either  side  at  the 
lower  border  of  this  muscle,  as  seen  in  fig.  88. 

Inserted,  by  strong  fleshy  fibres,  into  the  posterior  part  of  the 
middle  tendon. 

Use.  The  diaphragm  is  the  principal  agent  in  respiration, 
particularly  in  inspiration  :  for  when  it  is  in  action,  the  fibres, 
from  their  different  attachments,  endeavor  to  bring  themselves 

formed  in  the  interior  of  the  thorax  by  the  diaphragm  :  the  position  of  this  arch 
on  the  right  side,  is  indicated  by  a  dotted  line.  7z,  Columns,  or  crura  of  the 
lesser  muscles  of  the  diaphragm,  arising  from  the  lumbar  vertebrae,  i,  Leva- 
tores  costarum,  longiores,  and  breviores. 

I 


344  MUSCLES  OF    THE  ABDOMINAL  CAVITY. 

into  a  plain  towards  the  middle  tendon,  by  which  the  cavity 
of  the  thorax  is  enlarged,  particularly  at  the  sides,  where  the 
lungs  are  chiefly  situated ;  and  as  the  lungs  must  always  be 
contiguous  to  the  inside  of  the  thorax  and  upper  side  of  the 

Fig.  89  * 


diaphragm,  the  air   rushes   into   them,  in   order  to  fill    up  the 
increased  space.     This  muscle  is  assisted  by  the  two  rows  of 

*  The  under  or  abdominal  side  of  t*he  diaphragm.  J,  2,  3.  The  greater 
muscle  ;  the  figure  1  rests  upon  the  central  leaflet  of  the  tendinous  centre ;  the 
number  2  on  the  left  or  smallest  leaflet ;  and  number  3  on  the  right  leaflet.  4. 
The  thin  fasciculus  which  arises  from  the  ensiform  cartilage  ;  a  small  triangular 
space  is  left  on  either  side  of  this  fasciculus,  which  is  closed  only  by  the  serous 
membranes  of  the  abdomen  and  chest.  5.  The  ligamentum  arcuatum  exiernum 
of  the  left  side.  6.  The  ligamentum  arcuatum  internum  7.  A  small  arched 
opening  occasionally  found,  through  which  the  lesser  splanchnic  nerve  passes. 
8.  The  right  or  larger  tendon  of  the  lesser  muscle  ;  a  muscular  fasciculus  from 
this  tendon  curves  to  the  left  side  of  the  greater  muscle  between  the  cesophagea! 
and  aortic  openings.  9.  The  fourth  lumbar  vertebra.  10.  The  left  or  shorter 
tendon  of  the  lesser  muscle.  11.  The  aortic  opening  occupied  by  the  aorta, 
which  is  cut  short  off.  12.  A  portion  of  the  oesophagus  issuing  through  the 
cesophageal  opening.  13.  The  opening  for  the  inferior  vena  cava.  in  the  tendi- 
nous centre  of  the  diaphragm.  14.  The  psoas  magnus  muscle  passing  beneath 
the  ligamentum  arcuatum  internum  ;  it  has  been  removed  on  the  opposite  side 
to  show  the  arch  more  distinctly.  15.  The  quadratus  lumborum  passing  be- 
neath the  ligamentum  arcuatum  externum  ;  this  muscle  has  been  removed  on 
the  left  side. 


MUSCLES  OF    THE  ABDOMINAL  CAVITY.  345 

intercostals,  which  elevate  the  ribs,  and  the  cavity  of  the  thorax 
is  more  enlarged.  In  time  of  violent  exercise,  or  whatever 
cause  drives  the  blood  with  unusual  celerity  towards  the  lungs, 
the  pectoral  muscles,  the  serrati  antici  majores,  the  serrati  pos- 
tici  superiores,  and  scaleni  muscles,  are  brought  into  action. 
These  effect  the  lateral  dilatation  of  the  thorax.  And  in  labo- 
rious inspiration,  the  muscles  which  arise  from  the  upper  part 
of  the  thorax,  when  the  parts  into  which  they  are  inserted  are 
fixed,  likewise  assist.  In  expiration,  the  diaphragm  is  relaxed 
and  pushed  up  by  the  pressure  of  the  abdominal  muscles  upon 
the  viscera  of  the  abdomen  ;  and  at  the  same  time  that  they 
press  it  upwards,  they  also,  together  with  the  sterno-costales 
and  serrati  postici  inferiores,  pull  down  the  ribs,  and  are  assist- 
ed, in  a  powerful  manner,  by  the  elasticity  of  the  cartilages 
that  join  the  ribs  to  the  sternum  ;  by  which  the  cavity  of  the 
thorax  is  diminished,  and  the  air  suddenly  pushed  out  of  the 
lungs :  and,  in  laborious  expiration,  the  quadrat!  lumborum, 
sacro-lumbales,  and  longissimi  dorsi,  concur  in  pulling  down 
the  ribs.  — The  diaphragm,  contributes  the  principal  share  to 
the  dilatation  of  the  chest  during  inspiration.  When  relaxed, 
the  diaphragm  is  arched,  and  the  top  of  the  arch  is  nearly  on 
a  horizontal  level  with  the  anterior  portion  of  the  fourth  rib,  as 
seen  in  fig.  88,  page  342.  When  contracted,  the  arch  is  flat- 
tened, (though  the  cordiform  tendon  itself,  is  but  little  depress- 
ed,) and  the  capacity  of  the  thorax  is  increased,  at  the  same 
time  that  the  abdominal  viscera  are  pressed  downwards,  so  as 
to  produce  the  protrusion  of  the  abdomen  observed  during  in- 
spiration. The  abdominal  muscles  and  the  diaphragm,  usually 
antagonize  each  other,  by  contracting  alternately.  Occasionally 
they  contract  in  unison,  as  in  straining  during  defecation,  parturi- 
tion, &c.,  and  compress  the  viscera  and  their  contents,  between 
the  two  planes  which  they  form,  with  such  force  as  to  give  rise 
at'  times  to  hernial  protrusions. 

— In  natural  tranquil  inspiration,  the  dilatation  of  the  chest  is 
effected  almost  wholly  by  the  diaphragm. — 
The  four  pair  are, 


346  MUSCLES  OF    THE  ABDOMINAL  CAVITY. 

1.   Quadratus  Lumborum. 

Arises,  somewhat  broad,  tendinous  and  fleshy,  from  the  poste- 
rior part  of  the  spine  of  the  os  ilium. 

Inserted  into  the  transverse  processes  of  all  the  vertebrae  of  the 
loins,  into  the  last  rib  near  the  spine,  and  by  a  small  tendon  into 
the  side  of  the  last  vertebra  of  the  back. 

Use.  To  move  the  loins  to  one  side,  pull  down  the  last  rib. 
and,  when  both  act,  to  bend  the  loins  forwards. 

2.  Psoas  Parvus. 

Arises,  fleshy,  from  the  sides  of  the  two  upper  vertebrae  of 
the  loins,  and  sends  off  a  small  long  tendon  which  ends  thin  and 
flat,  and  is 

Inserted  into  the  brim  of  the  pelvis,  at  the  junction  of  the  os 
ilium  and  pubis. 

Use.  To  assist  the  psoas  magnus  in  bending  the  loins  for- 
wards ;  and,  in  certain  positions,  to  assist  in  raising  the  pelvis. 

N.  B.    This  muscle  is  very  often  wanting. 

3.  Psoas  Magnus, 

Arises,  fleshy,  from  the  side  of  the  body  and  transverse  pro- 
cess of  the  last  vertebra  of  the  back ;  and,  in  the  same  manner, 
from  those  of  the  loins,  by  as  many  distinct  slips.  — At  its 
superior  portion,  this  muscle  is  covered  by  a  thin  fibrous 
expansion  which  is  attached  on  the  one  hand  to  the  points  of 
the  transverse  processes,  and  on  the  other  to  the  bodies  of  the 
upper  lumbar  vertebrae.  This  expansion,  the  arcus  interior 
of  Senac  and  Haller  (ligamentum  arcuatum  inter num),  sepa- 
rates the  psoas  from  the  diaphragm.  On  the  outer  side  of 
this  is  another  aponeurotic  arch,  called  ligamentum  arcuatum 
externum;  it  passes  from  the  outer  extremity  of  the  former, 
to  the  inferior  margin  of  the  last  rib,  embracing  in  its  curve 
below,  the  quadratus  lumborum  muscle.  Both  these  arches 
give  origin  on  their  upper  margin  to  fibres  of  the  lesser  mus- 
cle of  the  diaphragm,  and  serve  to  cut  off  more  effectually 
any  communication  between  the  thoracic  and  abdominal 
cavities. — 


MUSCLES  WITHIN  THE  PELVIS.  347 

Inserted,  tendinous,  into  -the  trochanter  minor  of  the  os 
femoris ;  and  fleshy  into  that  bone,  a  little  below  the  same 
trochanter. 

Use.  To  bend  the  thigh  forwards  ;  or,  when  the  inferior 
extremity  is  fixed,  to  assist  in  bending  the  body. 

4.    lliacus  Interims. 

Arises,  fleshy,  from  the  transverse  process  of  the  last  vertebra 
of  the  loins,  from  all  the  inner  lip  of  the  spine  of  the  os  ilium, 
from  the  edge  of  that  bone  between  its  anterior  spinous  process 
and  the  acetabulum,  and  from  most  of  the  hollow  part  of  the 
ilium.  It  joins  with  the  psoas  magnus,  over  the  pubis,  where 
it  begins  to  become  tendinous ;  and  is 

Inserted   along  with  it  on  the  trochanter  minor. 

Use.  To  assist  the  psoas  in  bending  the  thigh,  and  to  bring 
it  directly  forwards. 

N.  B.  The  insertion  of  the  two  last  muscles  should  not  be 
traced  till  the  muscles  of  the  thigh  are  dissected. 

Muscles  situated  within  the  Pelvis. 
Of  these  there  are  two  pair. 

1.    Obturator  Internus, 

Arises  from  more  than  one  half  of  the  internal  circumference 
of  the  foramen  thyroideum,  formed  by  the  os  pubis  and  ischium, 
and  from  the  upper  part  of  the  plane  of  the  ischium,  where  it 
joins  the  ilium.  Its  inner  face  is  covered  by  a  portion  of  the 
levator  ani ;  and  appears  to  be  divided  into  a  number  of  fascic- 
uli, which  unite,  and  form  a  roundish  tendon,  that  passes  out 
of  the  pelvis,  between  the  posterior  sacro-ischiatic  ligament  and 
tuberosity  of  the  os  ischium ;  where  it  passes  over  the  capsular 
ligament  of  the  thigh  bone,  it  is  enclosed  as  in  a  sheath,  by  the 
gemini  muscles. 

Inserted,  by  a  round  tendon,  into  the  large  pit  at  the  root  of 
the  trochanter  major. 

Use.    To  roll  the  os  femoris  obliquely  outwards. 

N.  B.  The  insertion  of  this  muscle  should  not  be  traced 
until  the  muscles  of  the  thigh,  to  which  it  belongs,  are  dissected. 


348  MUSCLES    OF    THE  BACK. 

2.    Coccygeus. 

Arises,  tendinous  and  fleshy,  from  the  spinous  process  of  the 
os  ischium,  and  covers  the  inside  of  the  posterior  sacro-ischiatic 
ligament ;  from  this  narrow  beginning,  it  gradually  increases 
to  form  a  thin  fleshy  belly,  interspersed  with  tendinous  fibres. 

Inserted  into  the  extremity  of  the  os  sacrum,  and  nearly  the 
whole  length  of  the  os  coccygis  laterally. 

Use.  To  support  and  move  the  os  coccygis  forwards,  and  to 
tie  it  more  firmly  to  the  sacrum. 


Muscles  situated  on  the  Posterior  Part  of  the  Truiik. 

These  may  be  divided  into  four  layers  and  a  single  pair. 
The  first  layer  consists  of  two  muscles,  which  cover  almost 
the  whole  posterior  part  of  the  trunk. 


Trapezius  sen  Cucullaris, 

Arises,  by  a  strong  round  tendon,  from  the  lower  part  of  the 
protuberance  in  the  middle  of  the  os  occipitis  behind  ;  and.  by 
a  thin  membranous  tendon,  which  covers  part  of  the 
splenius  and  com  plexus  muscles  from  the  rough  curved  line 
that  extends  from  the  protuberance  towards  the  mastoid 
process  of  tire  temporal  bone  ;  runs  down  along  the  nape  of 
the  neck,  where  it  seems  to  arise  from  its  fellow,  and  covers 
the  spinous  processes  of  the  superior  vertebrae  of  the  neck  ;  it 
rises  from  the  spinous  processes  of  the  two  inferior  cervical,  and 
from  the  spinous  processes  of  all  the  vertebrae  of  the  back : 
adhering  tendinous,  to, its  fellow,  the  whole  length  of  its  origin. 
The  junction  of  the  tendons  form  a  sort  of  elliptical  expansion 
on  the  back  of  the  neck. 

Inserted,  fleshy,  into  the  posterior  half  of  the  clavicle ; 
tendinous  and  fleshy,  into  the  acromion,  and  into  almost  all 
the  spine  of  the  scapula. 

Use.  Moves  the  scapula  according  to  the  three  different 
directions  of  its  fibres :  for  the  upper  descending  fibres  draw  it 
obliquely  upwards  ;  the  middle  transverse  straight  fibres  draw 


MUSCLES  OF    THE    BACK, 


349 


it  directly  backwards  ;  and  the  inferior  ascending  fibres  draw  it 
obliquely  downwards  and  backwards. 

Fig.  90.* 


*  Muscles  of  the  back ;  the  superficial  being  shown  upon  the  right,  and  the 
deeper  seated  on  the  left  side.  1.-  The  trapezius  muscle.  2.  The  tendinous 
portion  which  with  a  corresponding"  portion  in  the  opposite  muscle,  forms  the 
tendinous  ellipse  on  the  back  of  the  neck.  3.  The  acromion  process  and  spine 
of  the  scapula.  4.  The  latissimus  dorsi  muscle.  5.  The  deltoid.  6.  The 
muscles  of  the  dorsum  of  the  scapula,  infra-spinatus,  teres  minor,  and  teres 
major.  7.  The  external  oblique  muscle.  8.  The  gluteus  medius.  9.  The 
glutei  maximi.  10.  The  levator  anguli  scapulae.  11.  The  rhomboideus  minor. 
12.  The  rhomboideus  major.  13.  The  splenius  capitis  ;  the  muscle  immediately 
above,  and  overlaid  by  the  splenius,  is  the  complexus.  14.  The  splenius  colli, 
only  partially  seen  ;  the  common  origin  of  the  splenius  is  seen  attached  to  the 
spinous  processes  below  the  lower  border  of  the  rhomboideus  major.  15.  The 
vertebral  aponeurosis.  16.  The  serratus  posticus  inferior.  17.  The  supra-spi- 
natus  muscle.  18.  The  infra-spinatus.  19.  The  teres  minor  muscle.  20.  The 
teres  major.  21.  The  long  head  of  the  triceps,  passing  between  the  teres  minor 
and  major  to  the  upper  arm.  22.  The  serratus  magnus,  proceeding  forwards 
from  its  origin  at  the  base  of  the  scapula.  23.  The  internal  oblique  muscle. 

30 


350  MUSCLES    OF    THE    BACK. 

N.  B.  Where  it  is  inseparably  united  to  its  fellow  in  the 
nape  of  the  neck,  it  is  attached  to  the  Ligamentum  Nuchce,  or 
Colli.  — This  ligament  is  the  representative  of  an  important 
elastic  ligament  in  quadrupeds  which  by  its  peculiar  properties 
relieves  the  action  of  the  muscles,  in  supporting  the  heavy 
pendant  head.  The  two  trapezii  taken  together,  have  some 
resemblance  to  the  monk's  cmvl  hanging  over  the  neck,  hence 
the  name  of  cucullares  given  to  them.  When  the  trapezius 
is  dissected  on  both  sides,  the  two  muscles  represent  a  trapezium 
or  diamond  shaped  quadrangle  on  the  back  of  the  shoulders. 
The  anterior  border  of  each  muscle,  forms  in  the  neck  the  pos- 
terior boundary  of  the  posterior  triangle  of  the  neck,  so  impor- 
tant to  be  understood  in  the  operation  upon  the  subclavian  artery 
above  the  clavicle. — 

2.  Latissimus  Dorsi, 

Arises,  by  a  broad  thin  tendon,  from  the  posterior  part  of  the 
spine  of  the  os  ilium,  from  all  the  spinous  processes  of  the  os 
sacrum  and  vertebrae  of  the  loins,  and  from  the  seven  inferior 
ones  of  the  vertebrae  of  the  back ;  also  tendinous  and  fleshy, 
from  the  extremities  of  the  three  or  four  inferior  ribs,  a  little 
beyond  their  cartilages,  by  as  many  distinct  slips.  The  inferior 
fibres  ascend  obliquely,  and  the  superior  run  transversely,  over 
the  inferior  angle  of  the  scapula,  towards  the  axilla  where  they 
are  collected,  twisted,  and  folded.  — Sometimes  a  few  addi- 
tional fibres  of  the  muscle,  arise  from  the  inferior  angle  of  the 
scapula. — 

Inserted,  by  a  strong  thin  tendon,  into  the  inner  edge  of  the 
groove  for  lodging  the  tendon  of  the  long  head  of  the  biceps. 

Use.  To  pull  the  arm  backwards  and  downwards,  and  to  roll 
the  os  humeri. 

N.  B.  The  insertion  of  this  muscle  should  not  be  prosecuted 
till  the  muscles  of  the  os  humeri,  to  which  it  belongs,  are 
dissected. 

The  second  layer  consists  of  three  pair,  two  on  the  back,  and 
one  on  the  neck. 
On  the  back : 


MUSCLES  OF  THE  BACK.  351 

'  1.  Serratus  Posticus  Inferior, 

Arises ,  by  a  broad  thin  tendon,  in  common  with  thatj3f  the 
latissimus  dorsi,  from  the  spinal  process  of  the  two  inferior 
vertebrae  of  the  back,  and  from  the  three  superior  vertebrae  of 
the  loins. 

Inserted  into  the  lower  edge  of  the  four  inferior  ribs,  at  a 
little  distance  from  their  cartilages,  by  as  many  distinct  fleshy 
slips. 

Use.  To  depress  the  ribs  into  which  it  is  inserted. 

2.  Rhomboideus. 

This  muscle  is  divided  into  two  portions. 

1.  Rhomboideus  major,   arises,  tendinous,  from  the  spinous 
processes  of  the  five  superior  vertebrae  of  the  back. 

Inserted  into  all  the  basis  of  the  scapula  below  its  spine. 
Use.  To  draw  the  scapula  obliquely  upwards,  and   directly 
inwards. 

2.  Rhomboideus  minor,  arises,   tendinous,  from   the  spinous 
processes  of  the  three  inferior  vertebrae  of  the  neck,  and  from 
the  ligamentum  nuchae. 

Inserted  into  the  base  of  the  scapula,  opposite  to  its  spine. 
Use.  To  assist  the  former. 
On  the  neck : 

3.  Splenius, 

Arises,  tendinous,  from  the  four  superior  spinous  processes 
of  the  vertebrae  of  the  back :  tendinous  and  fleshy,  from  the 
five  inferior  of  the  neck,  and  adheres  firmly  to  the  ligamen- 
tum nuchae.  At  the  third  vertebra  of  the  neck,  the  splenii 
recede  from  each  other,  so  that  part  of  the  complexus  muscle  is 
seen. 

Inserted,  by  as  many  tendons,  into  the  five  superior  transverse 
processes  of  the  vertebrae  of  the  neck ;  and  tendinous  and 
fleshy,  into  the  superior  part  of  the  mastoid  process,  and  into  the 
os  occipitis,  where  it  joins  with  the  root  of  that  process. 

Use.  To  bring  the   head   and   upper  vertebrae   of  the   neck 


352  MUSCLES  OF  THE  BACK. 

backwards  laterally :  and,  when  both  act,  to  pull  the  head 
directly  backwards. 

N.  B.  Albinus  divides  this  muscle  into  two,  viz.  That  por- 
tion which  arises  from  the  five  inferior  spinous  processes  of  the 
neck,  and  is  inserted,  into  the  mastoid  process  and  os  occipitis, 
he  calls  splenius  capitis  ;  and  that  portion  which  arises  from 
the  third  and  fourth  of  the  ttack,  and  is  inserted  into  the  five 
superior  transverse  processes  of  the  neck,  is  called  by  him 
splenius  collL 

The  single  pair, 

Serratus  Superior  Posticus, 

Arises ,  by  a  broad  thin  tendon,  from  the  spinous  processes 
of  the  three  last  vertebrae  of  the  neck,  and  the  two  uppermost 
of  the  back. 

Inserted  into  the  second,  third,  fourth,  and  fifth  ribs,  by  as 
many  fleshy  slips. 

Use.  To  elevate  the  ribs,  and  dilate  the  thorax. 

The  third  layer  consists  of  three  pair  on  the  back,  and  three 
on  the  neck. 

Those  on  the  back  are, 

1.  Spinalis  Dorsi, 

Arises  from  the  spinous  processes  of  the  two  uppermost  ver- 
tebrae of  the  loins,  and  the  three  inferior  of  the  back,  by  as 
many  tendons. 

Inserted  into  the  spinous  processes  of  the  nine  uppermost 
vertebrae  of  the  back,  except  the  first,  by  as  many  tendons. 

Use.  To  erect  and  fix  the  vertebrae,  and  to  assist  in  raising 
the  spine. 

2.  Longissimus  Dorsi, 

Arises,  tendinous  without,  and  fleshy  within,  from  the  side, 
and  all  the  spinous  processes  of  the  os  sacrum ;  from  the  poste- 
rior spine  of  the  os  ilium ;  from  all  the  spinous  processes,  and 
from  the  roots  of  the  transverse  processes  of  the  vertebrae  of  the 
loins. 


MUSCLES  OF  THE  BACK  AND  NECK.  353 

Inserted  into  all  the  transverse  processes  of  the  vertebrae  of 
the  back,  chiefly  by  small  double  tendons  ;  also,  by  a  tendinous 
and  fleshy  slip,  into  the  lower  edge  of  all  the  ribs,  except  the 
two  inferior,  at  a  little  distance  from  their  tubercles. 

Use.  To  extend  the  vertebrae,  and  to  raise  and  keep  the  trunk 
of  the  body  erect. 

N.  B.  From  the  upper  part  of  this  muscle,  there  runs  up  a 
round  fleshy  portion  which  joins  with  the  cervicalis  descendens. 

3.  Sacro-Lumbalis, 

Arises,  in  common  with  the  longissimus  dorsi. 

Inserted  into  all  the  ribs,  where  they  begin  to  be  curved 
forwards,  by  as  many  long  and  thin  tendons  ;  and, 

From  the  upper  part  of  the  six  or  eight  lower  ribs,  arise  as 
many  bundles  of  thin  fleshy  fibres,  which  soon  terminate  in 
the  inner  side  of  this  muscle,  and  are  named  musculi  ad  sacro- 
lumbalem  accessorii. 

Use.  To  pull  the  ribs  down,  and  assist  in  erecting  the  trunk 
of  the  body. 

N.  B.  There  is  a  fleshy  slip  which  runs  from  the  upper  part 
of  this  muscle  into  the  fourth,  fifth,  and  sixth  transverse  pro- 
cesses of  the  vertebrae  of  the  neck,  by  three  distinct  tendons  : 
it  is  named  cervicalis  descendens ;  and  its  use  is  to  turn  the  neck 
obliquely  backwards,  and  to  one  side. 

On  the  neck  are, 

1.   Complexus, 

Arises  from  the  transverse  processes  of  the  seven  superior 
vertebrae  of  the  back,  and  four  inferior  of  the  neck,  by  as  many 
distinct  tendinous  origins  ;  in  its  ascent,  it  receives  a  fleshy  slip 
from  the  spinous  process  of  the  first  vertebra  of  the  back.  From 
these  different  origins  it  runs  upwards,  and  is  every  where 
intermixed  with  tendinous  fibres. 

Inserted,  tendinous  and  fleshy,  into  the  inferior  edge  of  the 
protuberance  in  the  middle  of  the  os  occipitis,  and  into  a  part 
of  the  curved  line  that  runs  forwards  from  that  protuberance. 
30* 


354  MUSCLES  OF  THE  BACK  AND  NECK. 

Use.  To  draw  the  head  backwards,  and  to  one  side,  and 
when  both  act,  to  draw  the  head  directly  backwards. 

N.  B.  The  long  portion  of  this  muscle  that  is  situated  next 
the  spinous  processes,  lies  more  loose,  and  has  a  roundish  tendon 
in  the  middle  of  it :  for  which  reason  Albinus  calls  it  biventer 

cervicis. 

• 

2.   Trachelo-Mastoideusj 

Arises  from  the  transverse  processes  of  the  three  uppermost 
vertebrae  of  the  back,  and  from  the  five  lowermost  of  the  neck, 
(where  it  is  connected  to  the  transversalis  cervicis,)  by  as  many 
thin  tendons,  which  unite  into  a  belly,  and  run  up  under  the 
splenius. 

Inserted  into  the  middle  of  the  posterior  side  of  the  mastoid 
process,  by  a  thin  tendon. 

Use.  To  assist  the  complexus  ;  but  it  pulls  the  head  more 
to  one  side. 

3.  Levater  Scapulae, 

Arises,  tendinous  and  fleshy,  from  the  transverse  processes 
of  the  five  superior  vertebrae  of  the  neck,  by  as  many  distinct 
slips,  which  soon  unite  to  form  a  muscle  that  runs  downwards 
and  outwards. 

Inserted,  fleshy,  into  the  superior  angle  of  the  scapula. 

Use.  To  pull  the  scapula  upwards  and  a  little  forwards. 

The  fourth  layer  consists  of  two  pair*  on  the  back,  two  on 
the  posterior  part  of  the  neck,  four  small  pair  situated  immedi- 
ately below  the  posterior  part  of  the  occiput,  and  three  on  the 
side  of  the  neck. 

On  the  back  are, 

1.    Scmi-Spinalis  Dorsi, 

Arises,  from  the  transverse  processes  of  the  seventh,  eighth, 
ninth,  and  tenth  vertebrae  of  the  back,  by  as  many  distinct 
tendons,  which  soon  grow  fleshy,  and  then  become  tendinous : 
and  are 

Inserted  into  the   spinous  processes  of  all  the    vertebrae  of 


MUSCLES  OF  THE  BACK  AND  NECK. 


355 


the  back  above  the  eighth,  and  into  the  two  lowermost  of  the 
neck,  by  as  many  tendons. 

Use.  To  extend  the  spine  obliquely  backwards. 

2.   Multifidus  Spina, 
Arises  from  the  side  and  spinous  processes  of  the  os  sacrum, 


Fig.  91* 


and  from  the  posterior  part  of  the  os 
ilium,  where  it  joins  with  the  sacrum  ; 
from  all  the  oblique  and  transverse 
processes  of  the  vertebra  of  the  loins ; 
from  all  the  transverse  processes  of 
the  vertebrae  of  the  back,  and  from 
those  of  the  neck,  except  the  three 
first,  by  as  many  distinct  tendons, 
which  soon  grow  fleshy,  run  in  an 
oblique  direction  ;  and  are 

Inserted,  by  distinct  tendons,  into  all 
the  spinous  processes  of  the  vertebras 
of  the  loins,  of  the  back,  and  of  the 
neck,  except  the  first. 

Use.  When  the  different  portions 
of  this  muscle  act  on  one  side,  they 
extend  the  back  obliquely,  or  move  it 
laterally ;  but  if  they  act  together  on 
both  sides,  they  extend  the  vertebrae 
backwards. 

On  the  posterior  part  of  the  neck 
are, 


*  Deep  seated  muscles  of  the  back.  1.  The  common  origin  of  the  erector 
spinae  muscle.  Under  which  term  is  included  three  muscles,  the  sacro-lumba- 
jis,  longissimus  dorsi,  and  spinalis  dorsi.  2.  The  sacro-lumbalis.  3.  The 
longissimus  dorsi.  4.  The  spinalis  dorsi.  5.  The  cervicalis  ascendens.  6. 
The  transversalis  colli.  7.  Th.e  trachelo-mastoideus.  8.  The  complexus.  9. 
The  transversalis  colli,  showing  its  origin.  10.  The  semispinalis  dorsi.  11. 
The  semispinalis  colli.  12.  The  rectus  posticus  minor.  13.  The  rectus  posticus 
major.  14.  The  obliquus  superior.  15.  The  obliquus  inferior.  16.  The  multi- 
fidus  spinae.  17.  The  levatores  costarum.  18.  Intertransversales.  19.  The 
quadratus  lumborum. 


356  MUSCLES  OF  THE  BACK  AND  NECK. 

1.  Semi-Spinalis  Colli, 

Arises  from  the  transverse  processes  of  the  uppermost  six 
vertebrae  of  the  back,  by  as  many  distinct  tendons  ascending 
obliquely  under  the  com  plexus. 

Inserted  into  the  spinous  processes  of  all  the  vertebrae  of 
the  neck,  except  the  first  and  the  last. 

Use.  To  extend  the  neck  obliquely  backwards. 

2.  Transversalis  Cotti, 

Arises  from  the  transverse  processes  of  the  five  uppermost 
vertebrae  of  the  back,  by  as  many  tendinous  and  fleshy  origins  ; 
runs  between  the  trachelo  mastoideus,  and  splenius  colli  and 
cervicalis  descendens. 

Inserted  into  the  transverse  processes  of  all  the  cervical  ver- 
tebrae, except  the  first  and  the  last. 

Use.  To  turn  the  neck  obliquely  backwards,  and  a  little  to 
one  side. 

Below  the  posterior  part  of  the  occiput  are, 

1.  Rectus  Capitis  Posticus  Major, 

Arises,  fleshy,  from  the  external  part  of  the  spinous  process 
of  the  second  vertebra  of  the  neck,  and  grows  broader  in  its 
ascent,  which  is  not  straight,  but  obliquely  outwards. 

Inserted,  tendinous  and  fleshy,  into  the  os  occipitis,  near  the 
rectus  capitis  lateralis,  and  the  insertion  of  the  obliquus  capitis 
superior. 

Use.  To  pull  the  head  backwards,  and  to  assist  a  little  in  its 
rotation. 

2.  Rectis  Capitis  Posticus  Minor. 

Arises,  by  a  narrow  beginning,  close  to  its  fellow,  from  a 
little  protuberance  in  the  middle  of  the  back  part  of  the  first 
vertebra  of  the  neck,  its  outer  edge  being  covered  by  the  rectus 
major. 

Inserted,  somewhat  broad,  into  the  sides  of  a  dimple  in  the 
os  occipitis,  near  its  foramen  magnum. 

Use.  To  assist  the  rectus  major  in  moving  the  head  back- 
wards. 


MUSCLES  OF  THE  BACK  AND  NECK.  357 

3.    Obliquus   Capitis  Superior. 

Arises  from  the  transverse  process  of  the  first  vertebra  of  the 
neck. 

Inserted,  tendinous  and  fleshy,  into  the  os  occipitis  behind 
the  back  part  of  the  mastoid  portion  of  the  temporal  bone,  and 
under  the  insertion  of  the  complexus  muscle. 

Use.    To  draw  the  head  backwards. 

4.   Obliquus   Capitis  Inferior. 

Arises,  fleshy,  from  the  spinous  process  of  the  second  verte- 
bra of  the  neck,  its  whole  length  ;  and,  forming  a  thick  fleshy 
belly,  is 

Inserted  into  the  transverse  process  of  the  first  vertebra  of 
the  neck. 

Use.   To  give  a  rotary  motion  to  the  head. 

On  the  side  of  the  neck  are, 

1.  Scalenus  Anticus, 

Arises  from  the  fourth,  fifth,  and  sixth  transverse  processes  of 
the  first  vertebra  of  the  neck,  by  as  many  tendons. 

Inserted,  tendinous  and  fleshy,  into  the  upper  side  of  the  first 
rib  near  its  cartilage. 

2.  Scalenus  Medius, 

Arises  from  all  the  transverse  processes  of  the  vertebra  of  the 
neck,  by  as  many  strong  tendons ;  the  nerves  to  the  superior 
extremity  pass  between  it  and  the  former. 

Inserted  into  the  upper  and  outer  part  of  the  first  rib,  from  its 
root,  to  within  the  distance  of  an  inch  from  its  cartilage. 

3.  Scalenus  Posticus, 

Arises  from  the  fifth  and  sixth  transverse  processes  of  the 
vertebrae  of  the  neck. 

Inserted  into  the  upper  edge  of  the  second  rib,  not  far  from 
the  spine. 

Use  of  the  three  scaleni ;  to  bend  the  neck  to  one  side  ;    or, 


358  MUSCLES  OF  THE  BACK  AND  NECK. 

when  the  neck  is  fixed,  to  elevate  the  ribs,  and  to  dilate  the 
thorax. 

There  are  a  number  of  small  muscles  situated  between  the 
spinous  and  transverse  processes  of  contiguous  vertebrae  ;  which 
are  accordingly  named, 

1.  Interfpinales   Cotti. 

The  space  between  the  spinous  processes  of  the  vertebrae  of 
the  neck,  most  of  which  are  bifurcated,  is  filled  up  with  these 
fleshy  portions  ;  each  of  which 

Arises,  double,  from  the  spinous  process  of  the  cervical 
vertebra  below,  and  ascends  to  be 

Inserted,  in  the  same  manner,  into  the  spinous  process  of  the 
vertebra  above.  They  are  five  in  number. 

Use.    To  draw  these   processes  nearer  to  each  other. 

2.  Intertransversales  Colli. 

They  begin  from  the  transverse  process  of  the  first  vertebra 
of  the  back,  and  fill  up  the  spaces  between  the  transverse 
processes  of  the  vertebrae  of  the  neck,  which  are  likewise 
bifurcated ;  and,  consequently,  there  are  six  distinct  double 
muscles,  which 

Arise  from  the  inferior  transverse  process  of  each  vertebra  of 
the  neck,  and  first  of  the  back,  and  are 

Inserted  into  the  transverse  processes  next  above. 

Use.  To  draw  these  processes  towards  each  other,  and  turn 
the  neck  a  little  to  one  side. 

Interspinales    Dor  si    et    Lumborum,    and    the    Intertransver- 
sales Dorsi, 

Are  rather  small  tendons  than  muscles,  serving  to  connect  the 
spinal  and  transverse  processes. 

Intertransversales  Lumborum, 

Are  four  distinct  small  bundles  of  flesh,  which  fill  up  the  space 
between  the  transverse  processes  of  the  vertebrae  of  the  loins, 
and  serve  to  draw  them  towards  each  other. 


MUSCLES  OF  THE  SUPERIOR  EXTREMITIES.  359 

MUSCLES    OF    THE    SUPERIOR    EXTREMITIES. 

THESE  may  be  divided  into  the  muscles  that  are  situated  on 
the  scapula,  on  the  os  humeri,  on  the  cubit  or  forearm,  and  on 
the  hand. 

Muscles  situated  on  the  Scapula. 

These  are  called  muscles  of  the  os  humeri ;  and  are  three 
behind,  one  along  its  inferior  costa,  two  before,  and  one  beneath 
it. 

Behind  are, 

1 .  Supra-spinatus , 

Arises,  fleshy,  from  all  that  part  of  the  base  of  the  scapula 
that  is  above  its  spine  ;  also  from  the  spine  and  superior  costa  ; 
passes  under  the  acromion,  and  adheres  to  the  capsular  ligament 
of  the  os  humeri. 

Inserted,  tendinous,  into  that  part  of  the  large  protuberance 
on  the  head  of  the  os  humeri,  that  is  next  the  groove  for  lodging 
the  tendon  of  the  long  head  of  the  biceps. 

Use.  To  raise  the  arm  upwards  ;  and,  at  the  same  time,  to 
pull  the  capsular  ligament  from  between  the  bones,  that  it  may 
not  be  pinched. 

2.  Infra-spinatus, 

Arises,  fleshy,  from  all  that  part  of  the  base  of  the  scapula 
that  is  between  its  spine  and  inferior  angle ;  and  from  the  spine 
as  far  as  the  cervix  of  the  scapula.  The  fibres  ascend  and 
descend  obliquely  towards  a  tendon  in  the  middle  of  the  mus- 
cle, which  runs  forwards,  and  adheres  to  the  capsular  ligament. 

Inserted,  by  a  thick  and  short  tendon,  into  the  upper  and 
middle  part  of  the  large  protuberance  on  the  head  of  the  os 
humeri. 

Use.  To  roll  the  humerus  outwards :  to  assist  in  raising,  and 
in  supporting  it  when  raised  ;  and  to  pull  the  ligament  from 
between  the  bones. 


360  MUSCLES  SITUATED   ON  THE  SCAPULA. 

JV.  J5.  These  two  muscles  are  covered  with  a  tendinous 
membrane,  from  which  a  number  of  their  fleshy  fibres  arise. 
It  serves  besides  to  strengthen  their  actions,  and  keeps  them 
from  swelling  too  much  outwardly  when  in  action. 

3.    Teres  Minor, 

Arises,  fleshy,  from  all  the* round  edge  of  the  inferior  costa  ol 
the  scapula,  and  runs  forwards  along  the  inferior  edge  of  the 
infra-spinatus  muscle,  and  adheres  to  the  ligament. 

Inserted,  tendinous,  into  the  back  part  of  the  large  protube- 
rance on  the  head  of  the  os  humeri,  a  little  behind  and  below 
the  termination  of  the  last  named  muscle. 

Use.  To  roll  the  humerus  outwards,  to  draw  the  humerus 
backwards  ;  and  to  prevent  the  ligament  from  being  pinched 
between  the  bones. 

Along  the  inferior  costa  of  the  scapula  is, 

Teres  Major, 

Arises,  fleshy,  from  the  inferior  angle  of  the  scapula,  and  from 
all  that  portion  of  its  inferior  costa  that  is  rough  and  thicker 
than  the  rest ;  its  fleshy  fibres  are  continued  over  part  of  the 
infra-spinatus  muscle,  to  which  they  firmly  adhere. 

Inserted,  by  a  broad,  short,  and  thin  tendon,  into  the  ridge  at 
the  inner  side  of  the  groove  for  lodging  the  tendon  of  the  long 
head  of  the  biceps,  along  with  the  latissirnus  dorsi. 

Use.  To  roll  the  humerus  inwards,  and  to  draw  it  backwards 
and  downwards. 

The  two  before  the  scapula  are, 

1.    Deltoides, 

Arises,  fleshy,  from  all  the  posterior  part  of  the  clavicle 
that  the  pectoralis  major  does  not  occupy ;  tendinous  and  fleshy, 
from  the  acromion,  and  lower  margin  of  almost  the  whole 
spine  of  the  scapula  opposite  to  the  insertion  of  the  cucullaris 
muscle ;  from  the  origins  it  runs  in  three  different  directions, 
i.  e.  from  the  clavicle  outwards  and  downwards ;  from  the 


MUSCLES  SITUATED  ON  THE  SCAPULA.  361 

spine  of  the  scapula  outwards,  forwards,  and  downwards  ;  and 
from  the  acromion,  straight  downwards  ;  and  is  composed  of  a 
number  of  fasciculi,  which  form  a  strong  fleshy  muscle^  that 
covers  the  anterior  part  of  the  joint  of  the  os  humeri. 

Inserted,  tendinous,  into  a  rough  protuberance  in  the  outer 
side  of  the  os  humeri,  near  its  middle,  where  the  fibres  of  this 
muscle  intermix  with  some  part  of  the  brachialis  externus. 

Use.  To  pull  the  arm  directly  outwards  and  upwards,  and 
a  little  forwards  or  backwards,  according  to  the  different  direc- 
tions of  its  fibres. 

. 

2.    Coraco-Brachialis, 

Arises,  tendinous  and  fleshy,  from  the  forepart  of  the  coracoid 
process  of  the  scapula ;  adhering  in  its  descent,  to  the  short 
head  of  the  biceps. 

Inserted,  tendinous  and  fleshy,  about  the  middle  of  the 
internal  part  of  the  os  humeri,  near  the  origin  of  the  third 
head  of  the  triceps,  called  brachialis  externus,  where  it  sends 
down  a  thin  tendinous  expansion  to  the  internal  condyle  of  the 
os  humeri. 

Use.   To  raise  the  arm  upwards  and  forwards. 

N.  B.  There  passes  a  nerve  through  this  muscle,  called 
musculo  cutaneus. 

The  one  beneath  the  scapula  is, 

Subscapularis, 

Arises,  fleshy,  from  all  the  base  of  the  scapula,  internally, 
and  from  its  superior  and  inferior  costae,  being  composed  of  a 
number  of  tendinous  and  fleshy  fasciculi,  which  make  prints 
on  the  bone  ;  they  all  join  together,  fill  up  the  hollow  of  the 
scapula,  and  pass  over  the  joint,  adhering  to  the  capsular 
ligament. 

Inserted,  tendinous,  into  the  upper  part  of  the  internal  protu- 
berance at  the  head  of  the  os  humeri. 

Use.  To  roll  the  humerus  inwards,  and  to  draw  it  to  the  side 
of  the  body  ;  and  to  prevent  the  capsular  ligament  from  being 
pinched. 

31 


362 


MUSCLES  SITUATED  ON  THE  OS  HUMERI. 


Muscles  situated  on  the  Os  Humeri. 
These  are  called 

Muscles  of  the  Cubit  or  Forearm. 

They  consist  of  two  before,  and  two  behind. 

Before  are, 

• 

Fig.  92  *  1.   Biceps  Flexor  Cubiti, 

Arises,  by  two  heads.  The  first  and 
outermost  called  longus,  begins  tendinous 
from  the  upper  edge  of  the  glenoid  cavity 
of  the  scapula,  passes  over  the  head  of 
the  os  humeri  within  the  joint ;  and,  in 
its  descent  without  the  joint,  is  enclosed  in 
a  groove  near  the  head  of  the  os  humeri, 
by  a  membranous  ligament  that  proceeds 
from  the  capsular  ligament  and  adjacent 
tendons.  The  second  or  innermost  head, 
called  brevis,  arises  tendinous  and  fleshy, 
from  the  coracoid  process  of  the  scapula, 
in  common  with  the  coraco-brachialis 
muscle.  A  little  below  the  middle  of 
the  forepart  of  the  os  humeri,  these  heads 
unite. 

Inserted,  by  a  strong  roundish  tendon, 
into  the  tubercle  on  the  upper  end  of  the 
radius  internally. 

Use.  To  turn  the  hand  supine,  and  to  bend  the  forearm. 
.ZV.  B.  At  the  bending  of  the  elbow,  where  it  begins  to  grow 
tendinous,  it  sends  off  an  aponeurosis  which  covers  all  the 
muscles  on  the  inside  of  the  forearm,  and  joins  with  another 
tendinous  membrane,  which  is  sent  off  from  the  triceps  ex- 
tensor cubiti,  covers  all  the  muscles  on  the  outside  of  the 

*  The  muscles  of  the  anterior  aspect  of  the  upper  arm.  1.  The  coracoid 
process  of  the  scapula.  2.  The  coraco-clavicular  ligament  (trapezoid),  passing 
upwards  to  the  scapular  end  of  the  clavicle.  3.  The  coraco-acromial  ligament, 
passing  outwards  to  the  acronaion.  4.  The  subscapularis  muscle.  5.  The 
teres  major.  6.  The  coraco-brachialis.  7.  The  biceps.  8.  The  upper  end  of 
the  radius.  9.  The  brachialis  anticus.  10.  The  internal  head  of  the  triceps. 


MUSCLES   SITUATED  ON  THE   OS  HUMERI. 


363 


forearm,  and  a  number  of  the  fibres,  from  opposite  sides, 
'decussate  each  other.  It  serves  to  strengthen  the  muscles,  by 
keeping  them  from  swelling  too  much  outwardly,  when  in 
action  ;  and  a  number  of  their  fleshy  fibres  take  their  origin 
from  it. 

2.  Brachialis  Interims,  ."r  fit* 

Arises,  fleshy,  from  the  middle  of  the  os  humeri,  at  each  side 
of  the  insertion  of  the  deltoid  muscle,  covering  all  the  inferior 
and  forepart  of  this  bone,  runs  over  the  joint  and  adheres  firmly 
to  the  ligament. 

Fig.  93.*  Inserted,  by  a    strong   tendon,  into 

the  coronoid  process  of  the  ulna. 

Use.    To  bend  the  forearm,  and  to 
prevent  the  capsular  ligament  of  the 
joint  from  being  pinched. 
Behind,  are 

1.   Triceps  Extensor  Cubiti, 

Arises,  by  three  heads  ;  the  first  call- 
ed longus,  somewhat  broad  and  tendi- 
nous, from  the  inferior  costa  of  the 
scapula,  near  its  cervix.  The  second 
head,  called  brevis,  arises  by  an  acute, 
tendinous,  and  fleshy  beginning,  from 
the  back  part  of  the  os  humeri,  a  little 
below  its  head,  outwardly.  The  third, 
called  brachiatis  externus,  arises  by 
an  acute  beginning,  from  the  back  part 
of  the  os  humeri.  These  three  heads 
unite  lower  than  the  insertion  of  the 
teres  major,  and  cover  the  whole  posterior  part  of  the  humerus, 
from  which  they  receive  addition  in  their  descent. 

*  A  posterior  view  of  the  arm,  showing  the  triceps  extensor  cubiti  muscle. 
1.  Its  external  head  called  brevis.  2.  Its  long  or  scapular  head.  3.  Its  inter- 
nal head,  called  in  contradistinction  with  a  muscle  on  the  front  of  the  arm, 
brachialis  externus.  4.  The  olecranon  process  of  the  ulna.  5.  The  radius.  6. 
The  capsular  ligament  of  the  shoulder  joint. 


364   MUSCLES  ON  THE  ANTERIOR  PART  OF  THE  FOREARM. 

Inserted  into  the  upper  and  external  part  of  the  process  oJ 
the  ulna,  called  olecranon,  and  partly  into  the  condyles  of  the 
os  humeri,  adhering  firmly  to  the  ligament. 

Use.    To  extend  the  forearm. 

2.  Anconeus, 

Arises,  tendinous,  from  tfre  posterior  part  of  the  external 
condyle  of  the  os  humeri ;  it  soon  grows  fleshy,  and  is  continued 
from  the  third  head  of  the  triceps. 

Inserted,  fleshy,  and  thin  into  a  ridge  on  the  outer  and  pos- 
terior edge  of  the  ulna,  being  continued  some  way  before  the 
olecranon,  and  covered  with  a  tendinous  membrane. 

Use.    To  assist  in  extending  the  forearm. 

Muscles  situated  on  the  Forearm. 

% 

These  may  be  divided  into  three  classes,  viz. 

1.  The  muscles  which  bend  and  extend  the  wrist,  and  of  course  the  whole  hand. 

2.  Those  which  bend  and  extend  the  fingers  exclusively. 

3.  Those  which  act  on  the  radius  so  as  to  roll  it  backwards  and  forwards  on  the 
ulna ;  which  are  called  supinators  and  pronators. 

The  flexors  both  of  the  wrist  and  fingers,  and  the  pronators,  lie  on  the  front  of 
the  forearm.  The  extensors  and  the  supinators  on  the  back. 

The  flexors  generally  originate  from  the  internal  condyle  of  the  os  humeri,  and 
the  parts  adjacent  to  it ;  the  extensors  from  the  external  condyle  of  the  same 
bone,  and  the  parts  which  are  near  it. 

In  the  following  description  they  are  arranged  in  the  order  in  which  they  occur 
in  the  dissection  of  the  arm  ;  beginning  with  those  which  originate  with  the 
internal  condyle,  without  regard  to  their  particular  functions. 

Muscles  on  the  anterior  part  of  the  Forearm. 

1.  Palmaris  Longus, 

Arises,  tendinous,  from  the  internal  condyle  of  the  os 
humeri,  soon  grows  fleshy,  and,  after  a  short  progress  sends 
off  a  long  slender  tendon. 

Inserted  into  the  ligamentum  carpi  annulare,  'and  into  a 
tendinous  membrane  that  is  expanded  on  the  palm  of  the 
hand,  named  aponeurosis  palmaris ;  which,  above,  begins 
at  the  transverse  or  annular  ligament  of  the  wrist,  and,  below,  is 
fixed  to  the  roots  of  the  fingers. 


MUSCLES  ON  THE  ANTERIOR  PART  OF  THE  FOREARM. 


365 


Use.  To  bend  the  hand,  and  to  stretch  the  membrane  that 
is  expanded  on  the  palm.  ^ 

N.  B.  This  muscle  is  sometimes  wanting,  but  the  aponeu- 
rosis  palmaris  is  always  to  be  found. 

2.  Pronator  Radii  Teres, 

Arises,  fleshy,  from  the  internal  condyle  of  the  os  humeri, 
Fig.  94.*         and  tendinous  from  the  coronoid  process  of 
the  ulna. 

Inserted,  thin,  tendinous,  and  fleshy,  into 
the  middle  of  the  posterior  part  of  the  radius. 
Use.    To  roll  the  radius,  together  with  the 
hand,  inwards, 

3.  Flexor  Carpi  Radialis, 
Arises,  tendinous  and  fleshy,  from  the 
internal  condyle  of  the  os  humeri,  and  from 
the  anterior  part  of  the  upper  end  of  the 
ulna,  where  it  firmly  adheres  to  the  pronator 
radii  teres. 

Inserted,  by  a  flat  tendon,  into  the  fore 
and  upper  part  of  the  metacarpal  bone  that 
sustains  the  forefinger,  after  running  through 
a  fossa  in  the  os  trapezium. 

Use.  To  bend  the  hand,  and  to  assist  in 
its  pronation. 

4.  Flexor  Carpi  Ulnaris, 
Arises,  tendinous,  from  the  internal  con- 
dyle of  the  os  humeri.     It  has,  likewise,  a 
small  fleshy  beginning  from  the  outer  side 

*  Superficial  layer  of  muscles  of  the  fore-arm.  1.  The  lower  part  of  the 
biceps,  with  its  tendon.  2.  A  part  of  the  brachialis  anticus,  seen  beneath  the 
biceps.  3.  A  part  of  the  triceps.  4.  The  pronator  radii  teres.  5.  The  flexor 
carpi  radialis.  6.  The  palmaris  longus.  7.  One  of  the  fasciculi  of  the  flexor 
sublimis  digitorum ;  the  rest  of  the  muscle  is  seen  beneath  the  tendons  of  the 
palmaris  longus  and  flexor  carpi  radialis.  8.  The  flexor  carpi  ulnaris.  9.  The 
palmar  fascia.  10.  The  palmaris  brevis  muscle.  11.  The  abductor  pollicis 
muscle.  12.  One  portion  of  the  flexor  brevis  pollicis  ;  the  leading  line  crosses 
a  part  of  the  abductor  pollicis.  13.  The  supinator  longus  muscle.  14.  The 
extensor  ossis  metacarpi,  and  extensor  primi  internodii  pollicis,  curving  around 
the  lower  border  of  the  fore-arm. 

31* 


366   MUSCLES  ON  THE  ANTERIOR  PART  OF  THE  FOREARM. 


of  the  olecranon,  between  which,  and  the  origin  from  the 
condyle,  there  is  a  space  left,  through  which  the  ulnar  nerve 
passes  to  the  forearm  ;  'and  a  number  of  its  fleshy  fibres  arise 
from  the  tendinous  membrane  that  covers  the  forearm. 

Fig.  95.*  Inserted,  by  a  short  strong  tendon,  into 

the  os  pisiforme.  At  a  little  distance  from 
its  insertion,  a  small  ligament  is  sent  off  to 
the  metacarpal  bone  that  sustains  the  little 
finger. 

Use.   To  assist  the  former  in  bending  the 
arm. 

5.  Flexor  Sublimis  Perforatus, 

Arises,  tendinous  and  fleshy,  from  the 
.internal  condyle  of  the  os  humeri ;  tendin- 
ous from  the  coronoid  process  of  the  ulna, 
near  the  edge  of  the  cavity  that  receives  the 
head  of  the  radius  ;  fleshy  from  the  tubercle 
of  the  radius  ;  and  membranous  and  fleshy 
from  the  middle  of  the  forepart  of  the 
radius,  where  the  flexor  pollicis  longus 
arises.  Its  fleshy  belly  sends  off  four  round 
tendons  before  it  passes  under  the  ligament 
of  the  wrist. 

Inserted  into  the  anterior  and  upper  part 
of  the  second  bone  of  each  finger,  being  near 
the  extremity  of  the  first  bone,  and  divided 
for  the  passage  of  the  perforans. 
Use.   To  bend  the  second  joint  or  phalanx  of  the  fingers. 

6.  Flexor  Profundus  Perforans, 
Arises,  fleshy,  from  the  external  side,  and  upper  part  of  the 

*  The  deep  layer  of  muscles  on  the  forearm,  i.  The  internal  lateral  liga- 
ment of  the  elbow  joint.  2.  The  anterior  ligament.  3.  The  orbicular  ligament 
of  the  head  of  the  radius.  4.  The  flexor  profundus  digitorum  muscle.  5.  The 
flexor  longus  pollicis.  6.  The  pronator  quadratus.  7.  The  adductor  pollicis 
muscle.  8.  The  dorsal  interosseous  muscle  of  the  middle  finger,  and  palmar 
interosseous  of  the  ring  finger.  9.  The  dorsal  interosseous  muscle  of  the  ring 
linger  and  palmar  interosseous  of  the  little  finger. 


MUSCLES  ON  THE  BACK  OF  THE  FOREARM.  367 

ulna,  for  some  way  downwards,  and  from  a  large  share  of  the 
interosseous  ligament.  It  splits  into  four  tendons,  a  little  before 
it  passes  under  the  ligamentum  carpi  annulare ;  and  these  pass 
through  the  slits  in  the  tendons  of  the  flexor  sublimis. 

Inserted  into  the  fore  and  upper  part  of  the  third  or  last  bone 
of  all  the  four  fingers. 

Use.   To  bend  the  last  joint  of  the  fingers. 

7.    Flexor  Longus  Pollicis  Manus, 

Arises,  by  an  acute  fleshy  beginning,  from  the  upper  part  of 
the  radius,  immediately  below  its  tubercle,  and  is  continued  down 
for  some  space  on  the  forepart  of  this  bone.  It  has  likewise 
generally  another  origin  from  the  internal  condyle  of  the  os 
humeri,  which  forms  a  distinct  fleshy  slip,  that  terminates  near 
the  upper  part  of  the  origin  from  the  radius. 

Inserted  into  the  last  joint  of  the  thumb,  after  having  passed 
its  tendon  under  the  ligament  of  the  wrist. 

Use.   To  bend  the  last  joint  of  the  thumb.* 

8.  Prenator  Radii  Qwdratiu, 

Arises,  broad,  tendinous,  and  fleshy  from  the  lower  and  inner 
part  of  the  ulna  ;  the  fibres  run  transversely,  to  be 

Inserted  into  the  lower  and  anterior  part  of  the  radius,  oppo- 
site to  its  origin. 

Use.    To  turn  the  radius,  together  with  the  hand,  inwards. 

Muscles  of  the  External  Side  and  Back  of  the  Arm. 
1 .  Supinator  Radii  Longus, 

Arises,  by  an  acute  and  fleshy  origin,  from  the  external  ridge 
of  the  os  humeri,  above  the  external  condyle,  nearly  as  far  up  as 
the  middle  of  that  bone. 

*  The  thumb  has  but  one  flexor  muscle  on  the  front  of  the  arm,  although  it 
has  three  extensors  on  the  back  part.  — No  animal  but  man  has  a  distinct 
flexor  lengus  pollicis  muscle.  In  the  monkey  even,  its  place  is  supplied  by  a 
branch  of  the  communis  digitorum  tendons  ;  man  only  can  bring  the  thumb  in 
direct  opposition  to  the  fingers,  and  make  the  hand  a  perfect  instrument  of 
prehension. — P. 


368 


MUSCLES  ON  THE  BACK  OF  THE  FOREARM. 


Fig.  96.< 


Inserted  into  the  outer  side  of  the  infe- 
rior extremity  of  the  radius. 

Use.  To  roll  the  radius  outwards,  and 
consequently  the  palm  of  the  hand  up- 
wards. 

2.  Extensor  Carpi  Radialis  Longior, 
Arises,  broad,  thin,  and   fleshy,  immedi- 
ately below  the  supinator  radii  longus,  from 
the  lower  part  of  the  external  ridge  of  the  os 
humeri,  above  its  external  condyle. 

Inserted,  by  a  round  tendon,  into  the  pos- 
terior and  upper  part  of  the  metacarpal  bone 
that  sustains  the  fore-finger. 

Use.  To  extend  and  bring  the  hand  back- 
wards. 

3.  Extensor  Carpi  Radialis  Brevior, 
Arises,  tendinous,  from  the  external  con- 
dyle of  the  os  humeri,  and  from  the  ligament 
that  connects  the  radius  to  it,  and  runs  along 
the  outside  of  the  radius. 

Inserted,  by  a  round  tendon,  into  the 
upper  and  back  part  of  the  metacarpal  bone 
that  sustains  the  middle  finger. 


Use.    To  assist  the  last  mentioned  muscle. 


4.  Extensor  Carpi  Ulnaris, 
Arises,  tendinous  from  the  external  condyle  of  the  os  humeri, 

*  The  superficial  layer  of  muscles  on  the  posterior  aspect  of  the  fore-arm. 

I.  The  lower  part  of  the  biceps.    2.  Part  of  the  brachialis  anticus.     3.  The 
lower  part  of  the  triceps,  inserted  into  the  olecranon.    4.  The  supinaver  longus, 
5.  The  extensor  carpi  radialis  longior.     6.  The  extensor  carpi  radialis  brevier. 
7.  The  tendons  of  insertion  of  these  two  muscles.    8.  The  extensor  communis 
digitorum.     9.    The  extensor  minimi  digiti.     10.  The  extensor  carpi  ulnaris. 

II.  The  anconeus.     12.  Part  of  the  flexor  carpi  ulnaris.     13.  The  extensor  ossis 
metacarpi  and  extensor  primi  internodii  muscle,  lying  together.      14.    The 
extensor  secundi  internodii ;  its  tendon  is  seen  crossing  the  two  tendons  of  the 
extensor  carpi  radialis  longior  and  brevior.     15.  The  posterior  annular  ligament. 
The  tendons  of  the  common  extensor  are  seen  upon  the  back  of  the  hand,  and 
their  mode  of  distribution  on  the  dorsum  of  the  lingers. 


MUSCLES  ON  THE  BACK  OF  THE  FOREARM.  369 

and  in  its  progress,  fleshy,  from  the  middle  of  ihe  ulna,  where 
it  passes  over  the  ulna.  Its  round  tendon  is  enclosed  by  a 
membranous  sheath,  in  a  groove  which  is  situated  at  the  ex- 
tremity of  the  ulna. 

Inserted,  by  its  round  tendon,  into  the  posterior  and  upper 
part  of  the  metacarpal  bone  that  sustains  the  little  finger. 

Use.  To  assist  the  former  in  extending  the  hand. 


f 
)g,  froi 


5.  Extensor  Digitorum  Communis, 

Arises,  by  an  acute,  tendinous,  and  fleshy  beginning,  from 
the  external  condyle  of  the  os  humeri,  where  it  adheres  to  the 
supinator  radii  brevis.  Before  it  passes  under  the  ligamentum 
carpi  annulare  externum,  it  splits  into  four  tendons ;  some  of 
which  may  be  divided  into  several  smaller ;  and  about  the  fore- 
part of  the  metacarpal  bones  they  remit  tendinous  filaments  to 
each  other. 

Inserted  into  the  posterior  part  of  all  the  bones  of  the  four 
fingers,  by  a  tendinous  expansion. 

Vse.    To  extend  all  the  joints  of  the  fingers. 

6.  Supinator  Radii  Brevis, 

Arises,  tendinous,  from  the  external  condyle  of  the  os  humeri ; 
tendinous  and  fleshy,  from  the  external  and  upper  part  of  the 
ulna,  and  adheres  firmly  to  the  ligament  that  joins  these  two 
bones. 

Inserted,  into  the  head,  neck,  and  tubercle  of  the  radius,  near 
the  insertion  of  the  biceps,  and  into  the  ridge  running  from  that 
downwards  and  outwards. 

Use.  To  roll  the  radius  outwards,  and  so  bring  the  hand 
supine. 

7.    Indicator, 

Arises,  by  an  acute  fleshy  beginning,  from  the  middle  of  the 
posterior  part  of  the  ulna ;  its  tendon  passes  under  the  same 
ligament  with  the  extensor  digitorum  communis,  with  part  of 
which  it  is 

Inserted  into  the  posterior  part  of  the  fore-finger. 

Use.   To  extend  the  fore-finger  separately. 


370  MUSCLES  ON  THE  BACK  OF  THE  FOREARM. 

8.  Extensor  Ossis  Metacarpi  Pollicis  Manus. 
Arises,  fleshy,  from  the  middle  and  posterior  part  of  the  ulna, 
immediately  below  the  insertion  of  the  anconeus  muscle,  from 
Fig.  97.*          the  posterior  part  of  the  middle  of  the  radius, 
and  from  the  interosseous  ligament. 

Inserted,  generally  by  two  tendons,  into 
the  os  trapezium,  and  upper  back  part  of  the 
metacarpal  bone  of  the  thumb,  and  often 
joins  with  the  adductor  pollicis. 

Use.  To  extend  the  metacarpal  bone  of 
the  thumb,  outwardly. 

9.  Extensor  Primi  Internodii,  (Ext. 

Major  Pollicis  Manus,) 

Arises,  fleshy,  from  the  posterior  part  of 
the  ulna  near  the  former  muscle,  and  from 
the  interosseous  ligament. 

Inserted,  tendinous,  into  the  posterior  part 
of  the  first  bone  of  the  thumb  ;  and  a  part  of 
it  may  be  traced  as  far  as  the  second  bone. 

Use.  To  extend  the  first  bone  of  the 
thumb  obliquely  outwards. 

10.  Extensor  Secundi  Internodii,  (Ext. 

Minor  Pollicis  Manus,) 

Arises,  by  an  acute,  tendinous,  and  fleshy 
beginning,  from  the  middle  back  part  of  the  ulna,  and  from  the 
interosseous  ligament ;  its  tendon  runs  through  a  small  groove  at 
the  inner  and  back  part  of  the  lower  end  of  the  radius. 

Inserted  into  the  last  bone  of  the  thumb. 

Use.  To  extend  the  last  joint  of  the  thumb  obliquely  back- 
wards. 

*  The  deep  layer  of  muscles  on  the  posterior  aspect  of  the  fore-arm.  1.  The 
lower  part  of  the  humerus.  2.  The  olecranon.  3.  The  ulna.  4.  The  anconeus 
muscle.  5.  The  supinator  brevis  muscle.  6.  The  extensor  ossis  metacarpi 
pollicis.  7.  The  extensor  primi  internodii  pollicis.  8.  The  extensor  secundi 
internodii  pollicis.  9.  The  extensor  indicis.  10.  The  first  dorsal  interosseous 
muscle.  The  other  three  dorsal  interossei  are  seen  between  the  metacarpal 
bones  of  their  respective  fingers. 


MUSCLES  ON  THE  PALM  OF  THE  HAND.          371 

Muscles  on  the  Palm  of  the  Hand,. 

To  obtain  a  full  view  of  the  muscles  situated  on  the  palm  of  the  hand,  it  will 
be  necessary  to  remove  the  annular  or  transverse  ligament,  which  is  stretched 
across  from  the  projecting  points  of  the  pisiform  and  unciform  bones  on  the 
inside  of  the  wrist  to  the  scaphoid  and  trapezium  on  the  outside  j  for  the  pur- 
pose of  retaining  the  tendons  of  the  flexor  muscles  in  their  proper  situation. 
And  also,  to  remove  from  the  palm  of  the  hand  the  aponeurosis  palmaris, 
which  has  been  described  with  the  palmaris  longus  muscle. 

1.  Palmaris  Brevis. 

Arises  from  the  ligamentum  carpi  annulare,  and  the  apon- 
eurosis that  is  expanded  on  the  palm  of  the  hand. 

Inserted,  by  small  bundles  of  fleshy  fibres,  into  the  skin  and 
fat  that  cover  the  adductor  minimi  digiti,  and  into  the  os  pisi- 
forme. 

Use.   To  assist  in  contracting  the  palm  of  the  hand. 

2.  Abductor  Pollicis  Manus, 

Arises,  by  a  broad  tendinous  and  fleshy  beginning,  from  the 
ligamentum  carpi  annulare,  and  from  the  os  trapezium. 

Inserted^  tendinous,  into  the  outer  side  of  the  root  of  the 
first  phalanx  of  the  thumb. 

Use.    To  draw  the  thumb  from  the  fingers. 

3.  Flexor  Ossis  Metacarpi  Pollicis,  or  Opponens  Pollicis, 

Arises,  fleshy,  from  the  os  trapezium  and  ligamentum  carpi 
annulare,  lying  under  the  adductor  pollicis. 

Inserted,  tendinous  and  fleshy,  into  the  under  and  anterior 
part  of  the  metacarpal  bone  of  the  thumb. 

Use.  To  bring  the  thumb  inwards,  opposite  to  the  other 
finger. 

4.  Flexor  Brevis  Pollicis  Manus, 

Is  divided  into  two  portions  by  the  tendon  of  the  flexor 
longus  pollicis,  and  is  placed  beneath  the  adductor,  and  at  the 
side  of  the  opponens.  It  is  divided  into  two  heads.  The  first 
arises  fleshy  from  the  volar  sides  of  the  trapezium,  trapezoides, 
and  from  the  contiguous  part  of  the  internal  surface  of  the 
annular  ligament.  The  second  head  arises  from  the  magnum, 


372 


MUSCLES  ON  THE  PALM  OF  THE  HAND. 


unciforme,  and  from  the  base  of  the  metacarpal  bone  of  the 
middle  finger. 

Inserted)  by  the  first  head  into  the  outer  sesamoid  bone,  and 
by  the  second  into  the  inner  sesamoid  bones.  These  bones 
act  the  parts  of  patellae,  by  having  a  tendinous  connexion  with 
the  first  phalanx  of  the  thumb. 

Use.   To  bend  the  first  joirft  of  the  thumb. 


5.  Adductor  Potticis  Manus, 


Fig.  98.* 


Arises,  fleshy,  from  almost  the 
whole  length  of  the  metacarpal 
bone  that  sustains  the  middle 
finger ;  from  thence  its  fibres  are 
collected  together. 

Inserted,  tendinous,  into  the 
inner  part  of  the  root  of  the  first 
phalanx  of  the  thumb. 

Use.  To  pull  the  thumb  to- 
wards the  fingers. 

There  are  four  small  flexors, 
called,  from  their  form, 


6.  Lumbricales, 
Which  arise,  thin  and  fleshy, 
from   the  outside  of  the  tendons 
of  the  flexor  profundus,   a  little 
above  the  lower  edge  of  the  ligamentum  carpi  annulare. 

*  The  muscles  of  the  hand.  *1.  The  annular  ligament.  2,  2.  The  origin 
and  insertion  of  the  abductor  pollicis  muscle  ;  the  middle  portion  has  been 
removed.  3.  The  flexor  ossis  metacarpi,  or  opponens  pollicis.  4.  One  portion 
of  the  flexor  brevis  pollicis.  5.  The  deep  portion  of  the  flexor  brevis  pollicis. 
6.  The  adductor  pollicis.  7,  7.  The  lumbricales  muscles,  arising  from  the  deep 
flexor  tendons,  upon  which  the  numbers  are  placed.  The  tendons  of  the  flexor 
sublimis  have  been  removed  from  the  palm  of  the  hand.  8.  One  of  the  tendons 
of  the  deep  flexor,  passing  between  the  two  terminal  slips  of  the  tendon  of  the 
flexor  sublimis  to  reach  the  last  phalanx.  9.  The  tendon  of  the  flexor  longus 
pollicis,  passing  between  the  two  portions  of  the  flexor  brevis  to  the  last  pha- 
lanx. 10.  The  abductor  minimi  digiti.  11.  The  flexor  brevis  minimi  digiti. 
The  edge  of  the  flexor  ossis  metacarpi,  or  adductor  minimi  digiti,  is  seen  pro- 
jecting beyond  the  inner  border  of  the  flexor  brevis.  12.  The  prominence  of 
the  pisiform  bone.  13.  The  first  dorsal  interosseous  muscle. 


MUSCLES  ON  THE  PALM  OF  THE  HAND.  373 

Inserted,  by  long  slender  tendons,  into  the  outer  sides  of  the 
broad  tendons  of  the  interossei  muscles,  about  the  middle  of  the 
first  joint. 

Use.  To  increase  the  flexion  of  the  fingers  while  ;the  long 
flexors  are  in  full  action. 

7.  Adductor  Metacarpi  Minimi  Digiti  Manus, 

Arises,  fleshy  from  the  thin  edge  of  the  os  unciforme,  and 
from  that  part  of  the  ligament  of  the  wrist  next  to  it. 

Inserted,  tendinous,  into  the  inner  side  and  anterior  part  of  the 
metacarpal  bone  of  this  finger. 

Use.  To  bend  and  bring  the  metacarpal  bone  of  this  finger 
towards  the  wrist. 

8.  Flexor  Parvus  Minimi  Digiti, 

Arises,  fleshy,  from  the  outer  side  of  the  os  unciforme,  and 
from  the  ligament  of  the  wrist  which  joins  with  that  bone. 

Inserted,  by  a  roundish  tendon,  into  the  inner  and  anterior 
part  of  the  upper  end  of  the  first  bone  of  this  finger. 

Use.    To  bend  the  little  finger,  and  assist  the  adductor. 

9.  Abductor  Minimi  Digiti  Manus. 

Arises,  fleshy,  from  the  os  pisiforme,  and  from  that  part  of  the 
ligamentum  carpi  annulare  next  it. 

Inserted,  tendinous,  into  the  inner  side  of  the  upper  end  of 
the  first  bone  of  the  little  finger. 

Use.    To  draw  this  finger  from  the  rest. 

The  spaces  between  the  metacarpal  bones  are  occupied  by 
muscles,  called,  from  their  situation,  interosseous.  The  four 
following  are  to  be  seen  on  the  palm  of  the  hand. 

Anterior  Interosseous  Muscles. 

1.  Prior  Indicis. 

Arises,  tendinous  and  fleshy,  from  the  upper  and  outer  part  of 
the  metacarpal  bone  that  sustains  the  fore-finger. 

Inserted   into    the   outside   of    that    part   of     the    tendinous 
32 


374          MUSCLES  ON  THE  BACK  OF  THE  HAND. 

expansion  from  the  extensor  digitorum  communis,  which  covers 
the  posterior  part  of  the  fore-finger. 

Use.  To  draw  the  fore-finger  outwards  towards  the  thumb, 
and  extend  it  obliquely. 

2.  Posterior  Indicis. 

Arises  tendinous  and  fleshy  f  from  the  root  and  inner  part  of 
the  metacarpal  bone  that  sustains  the  fore-finger. 

Inserted  into  the  inner  side  of  the  tendinous  expansion  which 
is  sent  off  from  the  extensor  digitorum  communis,  along  the 
posterior  part  of  the  fore-finger. 

Use.  To  extend  the  fore-finger  obliquely,  and  to  draw  it 
inwards. 

3.  Prior  Annular  is. 

Arises,  from  the  root  of  the  outside  of  the  metacarpal  bone 
that  sustains  the  ring  finger. 

Inserted  into  the  outside  of  the  tendinous  expansion  of  the 
extensor  digitorum  communis  which  covers  the  ring  finger. 

Use.    To  extend  and  pull  the  ring  finger  towards  the  thumb. 

4.    Interosseous  Auricularis, 

Arises,  from  the  root  and  outer  side  of  the  metacarpal  bone 
of  the  little  finger ;  and  is 

Inserted  into  the  outside  of  the  tendinous  expansion  of  the 
extensor  digitorum  communis,  which  covers  the  posterior  part  of 
the  little  finger. 

Use.    To  extend  and  draw  the  little  finger  outwards. 

On  the  back  of  the  hand  three  muscles  of  the  same  kind  are 
to  be  seen,  which  also  appear  on  the  palm. 

Posterior  Interosseous  Muscles. 

,      1.  Prior  Medii, 

Arises,  by  two  origins,  from  the  root  of  the  metacarpal  bones 
that  sustain  the  fore  and  middle  fingers  externally,  and  next  each 
other :  runs  along  the  outside  of  the  middle  finger ;  and,  being 
conspicuous  on  both  sides  of  the  hand,  is 


MUSCLES  OF  THE  OS  FEMOR1S.  375 

Inserted  into  the  outside  of  the  tendinous  expansion  from  the 
extensor  digitorum  communis,  which  covers  the  posterior  jpart  of 
the  middle  finger. 

Use.    To  extend  and  to  draw  the  middle  finger  outwards. 

2.  Posterior  Medii, 

Arises,  by  two  origins,  from  the  roots  of  the  metacarpal  bones 
next  each  other,  that  sustain  the  middle  and  ring  fingers. 

Inserted  into  the  inside  of  the  tendinous  expansion  from  the 
extensor  digitorum  communis,  which  runs  along  the  posterior  part 
of  the  middle  finger. 

Use.    To  extend  and  draw  the  middle  finger  inwards. 

3.  Posterior  Annularis, 

Arises,  by  two  origins,  from  the  roots  of  the  metacarpal  bones 
that  sustain  the  ring  and  little  fingers,  next  each  other. 

Inserted  into  the  inside  of  the  tendon  on  the  back  of  the  ring 
finger. 

Use.    To  draw  the  ring  finger  inward. 

The  following  muscle  also  appears  on  the  back  of  the  hand. 

Adductor  Indicis  Manus, 

Arises,  from  the  os  trapezium,  and  from  the  superior  part  and 
inner  side  of  the  metacarpal  bone  of  the  thumb. 

Inserted,  by  a  short  tendon,  into  the  outer  and  back  part  of 
the  first  bone  of  the  fore  finger. 

Use.    To  bring  the  fore  finger  towards  the  thumb. 

MUSCLES    OF    THE    INFERIOR    EXTREMITIES. 

THESE  may  be  divided  into  the  muscles  situated  on  the  out- 
side  of  the  pelvis,  on  the  thigh,  on  the  leg,  and  on  the  foot. 

The  muscles  on  the  outside  of  the  pelvis,  which  are  called 
muscles  of  the  thigh, 

Are  composed  of  one  layer  before  and  three  layers  behind. 

The  layer  before  consists  of  five  muscles : 

1.  Psoas  Magnus.         ~)      c 

~    ir  >      See  page  346,  347. 

2.  lliacus  Internus.       ) 


376  MUSCLES  or  THE  os  FEMORIS. 

3.  Pectinalis, 

Arises,  broad  and  fleshy,  from  the  upper  and  anterior  part  of 
the  os  pubis  or  pectinis,  immediately  above  the  foramen  thy- 
roideum. 

Inserted  into  the  anterior  and  upper  part  of  the  linea  aspera 
of  the  os  femoris,  a  little  belo^v  the  trochanter  minor,  by  a  flat 
and  short  tendon. 

Use.  To  bring  the  thigh  upwards  and  inwards,  and  to  give  it  a 
degree  of  rotation  outwards. 

4.   Triceps  Adductor  Femoris, 

Under  this  appellation  are  comprehended  three  distinct 
muscles : 

a.  Adductor  Longus  Femoris, 

Arises,  by  a  strong  roundish  tendon,  from  the  upper  and 
anterior  part  of  the  os  pubis,  and  from  the  symphysis  pubis,  on 
the  inner  side  of  the  pectinalis. 

Inserted,  tendinous,  near  the  middle  of  the  posterior  part  of  the 
linea  aspera,  being  continued  for  some  way  down. 

b.  Adductor  Brevis  Femoris, 

Arises,  tendinous,  from  the  os  pubis  near  its  joining  with  the 
opposite  os  pubis,  below  and  behind  the  former. 

Inserted,  tendinous  and  fleshy,  into  the  inner  and  upper  part 
of  the  linea  aspera,  from  a  little  below  the  trochanter  minor,  to 
the  beginning  of  the  insertion  of  the  adductor  longus. 

c.  Adductor  Magnus  Femoris, 

Arises,  a  little  lower  down  than  the  former,  near  the  symphysis 
of  the  os  pubis,  tendinous  and  fleshy  from  the  tuberosity  of  the 
os  ischium ;  the  fibres  run  outwards  and  downwards. 

Inserted  into  almost  the  whole  length  of  the  linea  aspera  ; 
into  a  ridge  above  the  internal  condyle  of  the  os  femoris  ;  and, 
by  a  roundish  long  tendon,  into  the  upper  part  of  that  condyle, 


MUSCLES  OF  THE  OS  FEMORIS.  377 

a   little  above  which,  the   femoral    artery   takes   a   spiral    turn 
towards  the  ham,  passing  between  this  muscle  and  the  boiy?. 

Use  of  these  three  rrfuscles,  or  triceps.  To  bring  the  thigh 
inwards  and  upwards,  according  to  the  different  directions  of 
their  fibres ;  and,  in  some  degree,  to  roll  the  thigh  outwards. 

5.   Obturator  Externus, 

Arises,  fleshy,  from  the  lower  part  of  the  os  pubis,  and  fore- 
part of  the  inner  crus  of  the  ischium  ;  surrounds  the  foramen 
thyroideum ;  a  number  of  its  fibres,  arising  from  the  membrane 
which  fills  up  that  foramen,  are  collected  like  rays  towards  a 
centre,  and  pass  outwards  around  the  root  of  the  back  part  of 
the  cervix  of  the  os  femoris. 

Inserted,  by  a  strong  tendon,  into  the  cavity  at  the  inner  and 
back  part  of  the  root  of  the  trochanter  major,  adhering  in  its 
course  to  the  capsular  ligament  of  the  thigh  bone. 

Use.  To  roll  the  thigh  bone  obliquely  outwards,  and  to  pre- 
vent the  capsular  ligament  from  being  pinched. 

Behind  are, 

First  layer, 

Glutens  Maximus, 

Arises,  fleshy,  from  the  posterior  part  of  the  spine  of  the  os 
ilium,  a  little  higher  up  than  the  joining  of  the  ilium  with  the 
os  sacrum,  from  the  whole  external  side  of  the  os  sacrum,  be- 
low the  posterior  spinous  process  of  the  os  ilium  ;  from  the 
posterior  sacro-ischiatic  ligament,  over  which  part  of  the  in- 
ferior edge  of  this  muscle  hangs  in  a  folded  manner,  and  from 
the  os  coccygis.  All  the  fleshy  fibres  run  obliquely  forwards, 
and  a  little  downwards,  to  form  a  thick  broad  muscle,  which  is 
divided  into  a  number  of  strong  fasciculi.  The  upper  part  of 
it  covers  almost  the  whole  of  the  trochanter  major,  between 
which  and  the  tendon  of  this  muscle  there  is  a  lar^e  bursa  mu- 

O 

cosa,  and  where  it  is  inseparably  joined  to  the  broad  tendon  of 
the  tensor  vagina  femoris. 

Inserted,  by  a  strong,  thick,  and  broad  tendon,  into  the  upper 
and  outer  part  of  the  linea  aspera,  which   is  continued  from  the 
32* 


378  MUSCLES  OF  THE  OS  FEMORIS. 

troclianter  major,  for  some  way  downwards,  as  far  as  the  origin 
of  the  short  head  of  the  biceps  flexor  cruris — and  also  into  the 
fascia  femoris. 

Use.  To  extend  the  thigh,  by  pulling  it  directly  backwards, 
and  a  little  outwards. 

Second  layer, 

Glutens  Medius, 

Arises,  fleshy,  from  the  anterior  superior  spinous  process  of 
the  os  ilium,  and  from  all  the  outer  edge  of  the  spine  of  the 
ilium ;  except  its  posterior  part,  where  it  arises  from  the  dorsum 
of  that  bone. 

Inserted,  by  a  broad  tendon,  into  the  outer  and  upper  mar- 
gin of  the  trochanter  major. 

Use.  To  draw  the  thigh  bone  outwards,  and  a  little  back- 
wards ;  to  roll  the  thigh  bone  outwards,  especially  when  it  is 
bended. 

N.  B.  The  anterior  and  upper  part  of  this  muscle  is  covered 
by  a  tendinous  membrane,  from  which  a  number  of  its  fleshy 
fibres  arise,  and  which  joins  with  the  broad  tendons  of  the 
glutens  rnaximus,  tensor  vagina  femoris,  and  latissimus  dorsi. 

Third  layer  consists  of  four  muscles. 

1.  Glutens  Minimus. 

Arises,  fleshy,  from  a  ridge  that  is  continued  from  the  superior 
anterior  spinous  process  of  the  os  ilium,  and  from  the  middle 
of  the  dorsum  of  that  bone,  as  far  back  as  its  great  niche. 

Inserted,  by  a  strong  tendon,  into  the  fore  and  upper  part  of 
the  trochanter  major. 

Use.    To  assist  the  former  in  pulling  the  thigh  outwards  and 

backwards,  and  in  rolling  it. 
i 

2.  Pyriformis. 

Arises,  within  the  pelvis,  by  three  tendinous  and  fleshy  ori- 
gins, from  the  second,  third,  and  fourth  pieces  of  the  os  sacrum  ; 
from  thence  growing  gradually  narrower,  it  passes  out  of  the 


MUSCLES  OF  THE  OS  FEMORIS. 


379 


pelvis  along  with  the  posterior  crural  nerve,  below  the  niche  in 
the  posterior  part  of  the  os  ilium,  where  it  receives  a  few  fleshy 
fibres. 

Inserted,  by   a  roundish  tendon,  into  the  upper  part  of  the 
Fig.  99.*  cavity,  at   the   inner  side  of  the 

root  of  the  trochanter  major. 

Use.  To  move  the  thigh  a  lit- 
tle upwards,  and  roll  it  outwards. 

3.   Gemetti, 

Arise,  by  two  distinct  origins  ; 
the   superior  from    the    spinous 
process,  and    the    inferior   from 
the  tuberosity  of  the  os  ischium  ; 
also,   from  the   posterior  sacro- 
ischiatic    ligament.     They    are 
both  united  by  a  tendinous  fleshy 
membrane,  and  form  a  purse  for 
the  tendon  of  the  obturator  in- 
ternus    muscle,  which  was  for- 
merly described. 
Inserted,  tendinous  and  fleshy,  into   the  cavity  at   the  inner 
side  of  the  root  of  the  trochanter  major,  on  each  side  of  the 
tendon  of  the  obturator  internus,  to  which  they  firmly  adhere. 

Use.  To  roll  the  thigh  outwards,  and  to  preserve  the  tendon 
of  the  obturator  internus  from  being  hurt  by  the  hardness  of 
that  part  of  the  os  ischium  over  which  it  passes ;  also,  to 
hinder  it  from  starting  out  of  its  place,  while  the  muscle  is  in 
action. 


*  The  deep  muscles  of  the  gluteal  region.  1.  The  external  surface  of  the 
ilium.  2.  The  posterior  surface  of  the  sacrum.  3.  The  posterior  sacro-iliac 
ligaments.  4.  The  tuberosity  of  the  ischium.  5.  The  great  or  posterior  sacro- 
ischiatic  ligament.  6.  The  lessor  or  anterior  sacro-ischiatic  ligament.  7.  The 
trochanter  major.  8.  The  gluteus  minimus.  9.  The  pyriformis.  10.  The 
gemellus  superior.  11.  The  obturator  internus  muscle,  passing  out  of  the 
lesser  sacro-ischiatic  foramen.  12.  The  gemellus  inferior.  13.  The  quadratus 
femoris.  14.  The  tipper  part  of  the  adductor  magnus.  lo.  The  vastns  exfer- 
nus.  16.  The  biceps.  17.  The  gracilis.  18.  The  semi-tendinosus. 


380  MUSCLES  OF  THE  THIGH. 

4.   Quadratus  Femoris, 

Arises,  tendinous  and  fleshy,  from  the  outside  of  the  tuberosity 
of  the  os  ischium;  and,  running  transversely,  is 

Inserted,  fleshy,  into  a  rough  ridge,  continued  from  the  root 
of  the  large  trochanter  to  the  root  of  the  small  one. 

Use.    To  roll  the  thigh  outwards. 

Muscles  situated  on  the  Thigh. 

These  are  called  muscles  of  the  leg ;  and  consist  of  one,  on 
the  outside;  two  on  the  inside;  four,  before;  and  four,  behind. 

Previous  to  the  description  of  the  muscles  that  are  situated 
on  the  thigh  and  leg,  it  is  necessary  to  take  notice  of  a  broad 
tendinous  fascia  or  sheath,  (aponeurosis  of  the  lower  extremi- 
ties^) which  is  sent  off  from  the  back  and  from  the  tendon  of 
the  glutei  and  adjacent  muscles. 

It  is  a  strong  thick  membrane  on  the  outside  of  the  thigh 
and  leg  ;  but,  towards  the  inside  of  both,  it  gradually  turns 
thinner,  and  has  rather  the  appearance  of  cellular  substance 
than  a  tendinous  membrane.  A  little  below  the  trochanter 
major,  it  is  firmly  fixed  to  the  linea  aspera ;  and,  farther 
down,  to  that  part  of  the  head  of  the  tibia  that  is  next  the 
fibula  ;  where  it  sends  off  the  tendinous  expansion  along  the 
outside  of  the  leg. 

It  serves  to  strengthen  the  action  of  the  muscles,  by  keeping 
them  firm  in  their  proper  places  while  in  action,  particularly 
the  tendons  that  pass  over  the  joints  where  this  membrane  is 
thickest,  and  it  gives  origin  to  a  number  of.  the  fleshy  fibres  of 
the  muscles. 

On  the  outside  is, 

Tensor   Vagina  Femoris, 

Arises,  by  a  narrow,  tendinous,  and  fleshy  beginning,  from 
the  external  part  of  the  anterior  superior  spinous  process  of  the 
os  ilium. 

Inserted,  a  little  below  the  trochanter  major,  into  the  inner 
side  of  the  membranous  fascia  which  covers  the  outside  of  the 
thigh. 


MUSCLES  OF  THE  THIGH. 


381 


Fig.  100.* 


Use.  To  stretch  the  membranous 
fascia,  to  assist  in  the  adduction  of 
the  thigh,  and  somewhat  in  its  rota- 
tion inwards. 

On  the  inside  are, 

1 .   Sartorius, 

Arises,  tendinous,  from  the  anterior 
superior  spinous  process  of  the  os  ilium, 
soon  grows  fleshy,  runs  down  for  some 
space  upon  the  rectus,  and  going  oblique- 
ly inwards,  it  passes  over  the  vastus  in- 
ternus,  and,  about  the  middle  of  the  os 
femoris,  over  part  of  the  triceps ;  it 
runs  down  farther  between  the  tendon 
of  the  adductor  magnus  and  that  of  the 
gracilis  muscles. 

Inserted,  by  a  broad  and  thin  ten- 
don, into  the  inner  side  of  the  tibia, 
near  the  inferior  part  of  its  tubercle. 

Use.  To  bend  the  leg  obliquely  in- 
wards, or  to  bring  one  leg  across  the 
other. 


2.  Gracilis, 

Arises,  by  a  thin  tendon,  from  the  os  pubis,  near  the  symphy- 
sis  of  these  two  bones,  soon  grows  fleshy,  and,  descending  by 
the  inside  of  the  thigh,  is 

Inserted,  tendinous,  into  the  tibia  under  the  sartorius. 

Use.    To  assist  the  sartorius. 

Before  are, 

*  The  muscles  of  the  anterior  femoral  region.  1.  The  crest  of  the  ilium. 
2.  Its  anterior  superior  spinous  process.  3.  The  gluteus  medius.  4.  The  ten- 
sor vaginoe  femoris  ;  its  insertion  into  the  fascia  lata  is  shown  inferiorly.  5, 
The  sartorius.  6.  The  rectus.  7.  The  vastus  externus.  8.  The  vastus  inter- 
nus.  9.  The  patella.  10.  The  iliacus  internus.  11.  The  psoas  magnus. 
12.  The  pectineus.  13.  The  adductor  longus.  14.  Part  of  the  adductor  mag- 
nus. 15.  The  gracilis. 


382  MUSCLES  OF  THE  THIGH. 

1.  Rectus, 

Arises,  fleshy,  from  the  inferior  anterior  spinous  process  of  the 
os  ilium,  and  tendinous  from  the  dorsum  of  the  ilium,  a  little 
above  the  acetabulum ;  runs  down  over  the  anterior  part  of  the 
cervix  of  the  os  femoris ;  the  fibres  not  being  straight,  but 
running  down  like  the  plumage  of  a  feather  obliquely  outwards 
and  inwards,  from  a  tendon  in*  the  middle. 

Inserted,  tendinous,  into  the  upper  part  of  the  patella,  from 
which  a  thin  tendon  runs  down,  on  the  forepart  of  this  bone, 
to  terminate  in  a  thick  strong  ligament,  which  is  sent  off  from 
the  inferior  part  of  the  patella^  and  inserted  into  the  tubercle  of 
the  tibia. 

Use.  To  extend  the  leg,  and,  in  a  powerful  manner,  by  the 
intervention  of  the  patella,  like  a  pulley. 

2.  Vastus  ExternuSj 

Arises,  broad,  tendinous  and  fleshy,  from  the  root  of  the 
trochanter  major,  and  upper  part  of  the  linea  aspera  ;  its  origin 
being  continued  from  near  the  insertion  of  the  gluteus  minimus, 
the  whole  length  of  the  linea  aspera,  by  fleshy  fibres  which  run 
obliquely  forwards  to  a  middle  tendon,  where  they  terminate. 

Inserted  into  a  large  share  of  the  upper  part  of  the  patella ; 
and  part  of  it  ends  in  an  aponeurosis,  which  is  continued  down 
to  the  leg,  and  in  its  passage  is  firmly  fixed  to  the  head  of  the 
tibia. 

Use.    To  extend  the  leg. 

3.  Vastus  Interims, 

Arises,  tendinous  and  fleshy,  from  between  the  forepart  of  the 
os  femoris  and  root  of  the  trochanter  minor,  and  from  almost 
all  the  inside  of  the  linea  aspera,  by  fibres  running  obliquely 
forwards  and  downwards. 

Inserted,  tendinous,  into  the  upper  and  inside  of  the  patella, 
continuing  fleshy  lower  than  the  vastus  externus.  Part  of  it 
likewise  ends  in  an  aponeurosis  continued  down  to  the  leg,  and 
fixed  in  its  passage  to  the  upper  part  of  the  tibia. 

Use.    To  extend  the  leg. 


MUSCLES  OF  THE  THIGH, 


383 


Fig.  101.* 


4.   Cruralis, 

Arises,  fleshy,  from  between  the  two  trochanters  of  the  os 
femoris,  but  nearer  the  lesser  trochanter,  and  firmly  adhering 
to  most  of  the  forepart  of  the  os  femoris,  and  connected  to  both 
vasti  muscles. 

Inserted,   tendinous,    into   the   upper 
part  of  the  patella,  behind  the  rectus. 

Use.    To   assist  in   the   extension   of 
the  leg. 

N.  B.  These  four  muscles  before, 
being  inserted  into  the  patella,  have 
the  same  effect  upon  the  leg  as  if  they 
were  immediately  inserted  into  it  by 
means  of  the  strong  tendon,  or  rather 
ligament  which  is  sent  oft*  from  the 
inferior  part  of  the  patella  to  the  tibia. 
Behind  are, 

1 .  Semitendinosus, 
Arises,  tendinous  and  fleshy,  in  com- 
mon with  the  long  head  of  the  biceps, 
from  the  posterior  part  of  the  tubero- 
sity  of  the  os  ischium ;  and  sending 
down  a  long  roundish  tendon,  which 
ends  flat,  is 

Inserted,  into  the  inside  of  the  ridge 
of  the  tibia,  a  little  below  its  tubercle. 

Use.    To   bend    the   leg    backwards 
and  a  little  inwards. 


*  The  muscles  of  the  posterior  femoral  and  gluteal  region.  1.  The  gluteus 
medius.  2.  The  gluteus  maximus.  3.  The  vastus  externus  covered  in  by 
fascia  lata.  4.  The  long  head  of  the  biceps.  5.  Its  short  head.  6.  The  semi- 
tendinosus.  7.  The  semi-membranosus.  8.  The  gracilis.  9.  A  part  of  the 
inner  border  of  the  adductor  magnus.  10.  The  edge  of  the  sartorius.  11.  The 
popliteal  space.  12.  The  gastrocnemius  muscle:  its  two  heads.  The  tendon 
of  the  biceps  forms  the  outer  hamstring  ;  and  the  sartorius  with  the  tendons  of 
the  gracilis,  semi-tendinosus,  and  semi-membranosus,  the  inner  hamstring 


•384  MUSCLES  OF  THE  THIGH. 

2.    Semimembranosus, 

Arises,  tendinous,  from  the  upper  and  posterior  part  of  the 
tuberosity  of  the  os  ischium  ;  sends  down  a  broad  flat  tendon, 
which  ends  in  a  fleshy  belly,  and,  in  its  descent,  runs  at  first 
on  the  forepart  of  the  biceps,  and  lower,  between  it  and  the 

semitendinosus. 

• 

Inserted,  tendinous,  into  the  inner  and  back  part  of  the  head 
of  the  tibia. 

Use.    To  bend  the  leg,  and  bring  it  directly  backward. 

N.  B.    The  two  last  form  what  is  called  the  inner  hamstring. 

3.    Biceps  Flexor  Cruris, 

Arises  by  two  distinct  heads.  The  first,  called  longus,  arises, 
in  common  with  the  semitendinosus,  from  the  upper  and  pos- 
terior part  of  the  tuberosity  of  the  os  ischium.  The  second, 
called  brevis,  arises  from  the  linea  aspera,  a  little  below  the 
termination  of  the  gluteus  maxirnus,  by  a  fleshy  acute  begin- 
ning, which  soon  grows  broader  as  it  descends  to  join  with  the 
first  head,  a  little  above  the  external  condyle  of  the  os  femoris. 

Inserted,  by  a  strong  tendon,  into  the  upper  part  of  the  head 
of  the  fibula. 

Use.    To  bend  the  leg. 

JV.  B.  This  muscle  forms  what  is  called  the  outer  ham- 
string;  and  between  it  and  the  inner,  the  nervus  popliteus, 
the  arteria  and  vena  poplitea,  are  situated. 

4.  Popliteus, 

Arises,  by  a  round  tendon,  from  the  lower  and  back  part  of 
the  external  condyle  of  the  os  femoris,  then  runs  over  the  liga- 
ment that  involves  the  joint;  firmly  adhering  to  it,  and  part  of 
the  semilunar  cartilage.  As  it  runs  over  the  joint,  it  becomes 
fleshy,  and  the  fibres  run  obliquely  inwards,  being  covered 
with  a  thin  tendinous  membrane. 

Inserted,  broad,  thin  and  fleshy,  into  a  ridge  at  the  upper 
and  internal  edge  of  the  tibia,  a  little  below  its  head. 

Use.   To  assist  in  bending  the  leg,  and  to  prevent  the  cap- 


x  I 

MUSCLES  ON  THE  FRONT  OF  THE  LEG.          385 

sular  ligament  from   being   pinched.     After  the  leg  is  bent,  this 
muscle  serves  to  roll  it  inwards. 


Muscles  situated  on  the  Leg. 

These  muscles  may  be  arranged  in  the  two  general  classes  of  flexors  and  ex- 
tensors of  the  foot,  and  flexors  and  extensors  of  the  toes ;  but  several  of  them, 
viz.  the  tibialis  and  the  peronei,  produce  effects  which  are  different  from 
flexion  or  extension.  For  the  accommodation  of  the  student  of  anatomy,  they 
may  be  studied  in  the  order  of  their  position  as  they  lie  on  the  front,  on  the 
outside,  and  on  the  back  of  the  leg. 


Muscles  on  the  Front  of  the  Leg. 

1.   Tibialis  Anticus. 

Arises,  tendinous  and  fleshy,  from  the  middle  of  that  process 
of  the  tibia,  to  which  the  fibula  is  connected  above ;  then  it 
runs  down  fleshy  on  the  outside  of  the  tibia  ;  from  which,  and 
the  upper  part  of  the  interosseous  ligament,  it  receives  a  num- 
ber of  distinct  fleshy  fibres ;  near  the  extremity  of  the  tibia,  it 
sends  off  a  strong  round  tendon,  which  passes  under  part  of  the 
ligamentum  tarsi  annulare  near  the  malleolus  internus. 

Inserted,  tendinous,  into  the  inside  of  the  os  cuneiforme 
internum,  and  posterior  end  of  the  metatarsal  bone  that  sustains 
the  great  toe. 

Use.  To  bend  the  foot,  by  drawing  it  upwards,  and,  at  the 
same  time,  to  turn  the  toes  inwards. 

2.  Extensor  Proprius  Pollicis  Pedis, 

Arises,  by  an  acute,  tendinous,  and  fleshy  beginning,  some 
way  below  the  head  and  anterior  part  of  the  fibula,  along 
which  it  runs  to  near  its  lower  extremity,  connected  to  it  by  a 
number  of  fleshy  fibres,  which  descend  obliquely  towards  a 
tendon. 

Inserted,  tendinous,  into  the  posterior  part  of  the  first  and  last 
joint  of  the  great  toe. 

Use.    To  extend  the  great  toe. 
33 


386 


MUSCLES  ON  THE  FRONT  OF  THE  LEG. 


3.  Extensor  Longus  Digitorum  Pedis, 

Arises,  tendinous  and  fleshy,  from  the  upper  and  outer  part 
of  the  head  of  the  tibia,  and  from  the  head  of  the  fibula  where 
Fig.  102.*  it  joins  with  the  tibia,  and  from  the 

interosseous  ligament;  also  from  the 
tendinous  fascia,  which  covers  the  up- 
per and  outside  of  the  leg  by  a  number 
of  fleshy  fibres ;  and  tendinous  and 
fleshy  from  the  anterior  spine  of  the 
fibula,  almost  its  whole  length,  where  it 
is  inseparable  from  the  peroneus  tertius. 
It  splits  into  four  round  tendons,  under 
the  ligamentum  tarsi  annulare. 

Inserted,  by  a  flat  tendon,  into  the 
root  of  the  first  joint  of  each  of  the  four 
small  toes  ;  and  is  expanded  over  the 
upper  side  of  the  toes,  as  far  as  the  root 
of  the  last  joint. 

Use.  To  extend  all  the  joints  of  the 
four  small  toes. 

N.  B.  A  portion  of  this  muscle, 
which  is  called 

4.  Peroneus  Tertius, 

Arises,  from  the  middle  of  the  fibula, 
continues  down  to  near  its  inferior  ex- 
tremity, and  sends  its  fleshy  fibres  forwards  to  a  tendon,  which 
passes  under  the  annular  ligament,  and  is 


*  The  muscles  of  the  anterior  tibial  region.  1.  The  extensor  muscles  inserted 
into  the  patella.  2.  The  subcutaneous  surface  of  the  tibia.  3.  The  tibialis 
anticus.  4.  The  extensor  communis  digitorum.  5.  The  extensor  proprius 
pollicis.  6.  The  peroneus  tertius.  7.  The  peroneus  longus.  8.  The  peroneus 
brevis.  9,  9.  The  borders  of  the  soleus  muscle.  10.  A  part  of  the  inner  belly 
of  the  gastrocnemius.  11.  The  extensor  brevis  digitorura  ;  the  tendon  in  front 
of  this  number  is  that  of  the  peroneus  tertius ;  and  that  behind  it,  the  tendon 
of  the  peroneus  brevis. 


MUSCLES  ON  THE  LEG.  387 

Inserted,  into  the  root  of  the  metatarsal  bone  that  sustains  the 
little  toe. 

Use.   To  assist  in  bending  the  foot. 

Muscles  on  the  outside  of  the  Leg. 

1.  Peroneus  Longus. 

Arises,  tendinous  and  fleshy,  from  the  forepart  of  the  head  of 
the  peroneus,  or  fibula,  the  fibres  running  straight  down  ;  also 
from  the  upper  and  external  part  of  the  fibula,  where  it  begins 
to  rise  into  a  round  edge  ;  as,  also,  from  the  hollow  between  that 
and  its  anterior  edge,  as  far  down  as  to  reach  within  a  hand's 
breadth  of  the  ankle,  by  a  number  of  fleshy  fibres,  which  run 
outwards  towards  a  tendon,  that  subsequently  becomes  long  and 
round,  and  passes  through  a  channel  at  the  outer  ankle,  in  the 
back  part  of  the  inferior  extremity  of  the  fibula ;  then  being 
reflected  to  the  sinuosity  of  the  os  calcis,  it  runs  along  a 
groove  in  the  os  cuboides,  above  the  muscles  in  the  sole  of  the^ 
foot. 

Inserted,  tendinous,  into  the  outside  of  the  root  of  the  meta- 
tarsal bone  that  sustains  the  great  toe,  and  by°some  tendinous 
fibres  into  the  os  cuneiforme  internum. 

Use.    To  turn  the  foot  outwards,  and  to  extend  it  a  little. 

2.  Peroneus  Brevis, 

Arises,  by  an  acute  fleshy  beginning,  from  above  the  middle 
of  the  external  part  of  the  fibula ;  from  the  outer  side  of  the 
anterior  spine  of  this  bone  ;  as  also  from  its  round  edge  externally, 
the  fibres  running  obliquely  outwards  towards  a  tendon  on  its 
external  side :  it  sends  off  a  round  tendon  which  passes  through 
the  groove  at  the  outer  ankle,  being  there  included  under  the  , 
same  ligament  with  that  of  the  preceding  muscle ;  and  a  little 
farther,  it  runs  through  a  particular  one  of  its  own. 

Inserted,  tendinous,  into  the  root  and  external  part  of  the 
metatarsal  bone  that  sustains  the  little  toe. 

Use.  To  assist  the  former  in  pulling  the  foot  outwards,  and 
extending  it  a  little. 


MUSCLES  ON  THE  LEG. 

Muscles  on  the  Back  of  the  Leg. 
1.  Gastrocnemius  Externus,  seu  Gemellus, 

Arises,  by  two  distinct  heads.  The  first  head  arises  from  the 
Fig.  103.*  upper  and  back  part  of  the  internal  condyle 
of  the  os  femoris,  and  from  that  bone,  a  little 
above  its  condyle,  by  two  distinct  tendinous 
origins.  The  second  head  arises  tendinous 
from  the  upper  and  back  part  of  the  exter- 
nal condyle  of  the  os  femoris.  A  little  be- 
low the  joint,  their  fleshy  bellies  unite  in  a 
middle  tendon  ;  and,  below  the  middle  of 
the  tibia,  it  sends  off  a  broad  thin  tendon, 
which  joins  a  little  above  the  extremity  of 
the  tibia  with  the  tendon  of  the  following. 

2.  Soleus,  seu  Gastrocnemius  Internus, 
Arises  by  two  origins.  The  first  is  from 
the  upper  and  back  part  of  the  head  of  the 
fibula,  continuing  to  receive  many  of  its 
fleshy  fibres  from  the  posterior  part  of  that 
bone  for  some  space  below  its  head.  The 
other  origin  begins  from  the  posterior  and 
upper  part  of  the  middle  of  the  tibia  ;  and 
runs  inwards  along  the  inferior  edge  of  the 
popliteus  towards  the  inner  part  of  the  tibia, 
from  which  it  receives  fleshy  fibres  for  some 
way  down.  The  flesh  of  this  muscle, 
covered  by  the  tendon  of  the  gemellus,  runs  down  nearly  as  far 
as  the  extremity  of  the  tibia  ;  a  little  above  which  the  tendons  of 


*  The  superficial  muscles  on  the  posterior  surface  of  the  leg.  1.  Biceps 
flexor  cruris  muscle,  forming  the  outer  hamstring.  2.  The  tendons  forming 
the  inner  hamstring,  consisting  of  the  tendons  of  the  semitendinosus,  semi- 
membranosus,  gracilis  and  sartorius.  3.  The  popliteal  space.  4.  The  gastroc- 
nemius  muscle.  5,  5.  The  soleus  muscle.  6.  Tendo  Achillis.  7.  The  posterior 
tuberosity  of  the  os  calcis.  8.  The  tendons  of  the  peroneus  longus  and  brevis 
muscles,  passing  behind  the  outer  ankle.  9.  The  tendons  of  the  deep  layer  of 
muscles  passing  into  the  foot  behind  the  inner  ankle. 


MUSCLES  ON  THE  LEG. 


389 


both  gastrocnemii    unite,  and  form  a  strong   round  cord,  which 
is  called  tendo-Achillis. 

Inserted  into  the  upper  and  posterior  part  of  the  os  caleis,  by 
Fig.  104.*         the  projection  of  which  the  tendo-Achillis  is 
placed  at  a  considerable  distance  from  the 
tibia. 

Use.  To  extend  the  foot,  by  bringing  it 
backwards  and  downwards. 

3.  Plantaris. 

Arises,  thin  and  fleshy,  from  the  upper 
and  back  part  of  the  root  of  the  external 
condyle  of  the  os  femoris,  near  the  interior 
extremity  of  that  bone,  adhering  to  the  liga- 
.  ment  that  involves  the  joint  in  its  descent. 
It  passes  along  the  second  origin  of  the 
soleus  and  under  the  gemellus,  where  it 
sends  off  a  long,  slender,  thin  tendon,  which 
comes  from  between  the  great  extensors, 
where  they  join  tendons  ;  then  runs  down 
by  the  inside  of  the  tendo-Achillis. 

Inserted,  into  the  inside  of  the  posterior 
part  of  the  os  caleis,  below  the  tendo- 
Achillis. 

Use.  To  assist  the  former,  and  to  pull  the 
capsular  ligament  of  the  knee  from  between 
the  bones.  It  seems  likewise  to  assist  in  rolling  the  foot 
forwards, 

*  The  deep  layer  of  muscles  of  the  posterior  libial  region.  1.  The  lower 
extremity  of  the  femur.  2.  The  ligamentum  posticum  Winslowii.  3.  The 
tendon  of  the  semi-membranosus  muscle  dividing  into  its  three  slips.  4.  The 
internal  lateral  ligament  of  the  knee-joint.  5.  The  external  lateral  ligament. 
0.  The  popliteus  muscle.  7.  The  flexor  longus  digitorum.  8.  The  tibialis 
posticus.  9.  The  flexor  longus  pollicis.  10.  The  peroneus  longus  muscle. 
11.  The  peroneus  brevis.  12.  The  tendo-Achillis  divided  at  its  insertion  into 
the  os  caleis.  13.  The  tendons  of  the  tibialis  posticus  and  flexor  longus  digito- 
rum muscles,  just  as  they  are  about  to  pass  beneath  the  internal  annular  liga- 
ment of  the  ankle ;  the  interval  between  the  latter  tendon  and  the  tendon  of 
the  flexor  longus  pollicis  is  occupied  by  the  posterior  tibial  vessels  and  nerves. 

33* 


390  MUSCLES  ON  THE  LEG. 

4.  Flexor  Longus  Digitorum  Pcdis,  Profundus,  Perforans, 

Arises,  by  an  acute  tendon,  which  soon  becomes  fleshy  from 
the  back  part  of  the  tibia,  some  way  below  its  head,  near  the 
entry  of  the  medullary  artery  ;  which  beginning,  is  continued 
down  the  inner  edge  of  this  bone  by  short  fleshy  fibres,  ending 
in  its  tendon ;  also  by  tendinous  and  fleshy  fibres,  from  the  outer 
edge  of  the  tibia,  and  between  this  double  order  of  fibres,  the 
tibialis  posticus  muscle  lies  enclosed.  Having  passed  under  two 
annular  ligaments,  it  then  passes  through  a  sinuosity  at  the 
inside  of  the  os  calcis  ;  and  about  the  middle  of  the  sole  of  the 
foot,  divides  into  four  tendons,  which  passes  through  the  slit? 
of  the  perforatus  ;  and  just  before  its  division  it  receives  a  con- 
siderable tendon  from  that  of  the  flexor  pollicis  longus. 

Inserted  into  the  extremity  of  the  last  joint  of  the  four  lesser 
toes. 

Use.    To  bend  the  last  joint  of  the  toes. 

5.    Tibialis  Posticus, 

Arises,  by  a  narrow  fleshy  beginning,  from  the  fore  and  upper- 
part  of  the  tibia,  just  under  the  process  which  joins  it  to  the 
fibula  ;  then  passing  through  a  perforation  in  the  upper  part  of 
the  interosseous  ligament,  it  continues  its  origin  from  the  back 
part  of  the  fibula  next  the  tibia,  and  from  near  one  half  of  the 
upper  part  of  the  last  named  bone  ;  as  also,  from  the  interos- 
seous ligament,  the  fibres  running  towards  a  middle  tendon, 
which  sends  off  a  round  one  that  passes  in  a  groove  behind 
the  malleolus  internus. 

Inserted,  tendinous,  into  the  upper  and  inner  part  of  the  os 
naviculare,  being  farther  continued  to  the  os  cuneiforme  inter- 
num  and  medium  ;  besides  it  gives  some  tendinous  filaments  to 
the  os  calcis,  os  cuboides,  and  to  the  root  of  the  metatarsal  bone 
that  sustains  the  middle  toe. 

Use.    To  extend  the  foot,  and  to  turn  the  toes  inwards. 

6.  Flexor  Longus  Pollicis  Pedis, 

Arises,  by  an  acute,  tendinous,  and  fleshy  beginning,  from 
the  posterior  part  of  the  fibula,  some  way  below  its  head,  being 


MUSCLES  ON  THE   SOLE  OF   THE  FOOT.  391 

continued  down  the  same  bone,  almost  to  its  inferior  extremity, 
by  a  double  order  of  oblique  fleshy  fibres  ;  its  tendon  passes 
under  an  annular  ligament  at  the  inner  ankle. 

Inserted,  into  the  last  joint  of  the  great  toe,  and,  generally, 
sends  a  small  tendon  to  the  os  calcis. 

Use.    To  bend  the  last  joint  of  this  toe. 

On  the  upper  surface  of  the  foot  there  is  one  muscle,  viz. 

Extensor  Brevis  Digitorum  Pedis, 

Arises,  fleshy  and  tendinous,  from  the  fore  and  upper  part  of 
the  os  calcis  ;  and  soon  forms  a  fleshy  belly,  divisible  into  four 
portions,  which  send  off  an  equal  number  of  tendons  that  pass 
over  the  upper  part  of  the  foot,  under  the  tendons  of  the  for- 
mer. 

Inserted,  by  four  slender  tendons,  into  the  tendinous  expan- 
sion from  the  extensor  longus  which  covers  the  small  toes,  ex- 
cept the  little  one ;  also  into  the  tendinous  expansion  from  the 
extensor  pollicis,  that  covers  the  upper  part  of  the  great  toe. 

Use.    To  extend  the  toes. 

Muscles  on  the  Sole  of  the  Foot. 

On  the  sole  of  the  foot  there  is  a  strong  tendinous  membrane  called  Aponturosis 
Plantaris,  which  originates  from  the  tuberosity  of  the  os  calcis,  and  proceeds 
forward  to  the  toes,  increasing  gradually  in  breadth. 

It  is  divided  into  three  portions.  That  in  the  middle  is  the  largest ;  it  protects 
and  covers  the  short  flexor  muscles,  and  the  tendons  in  the  middle  of  the  foot. 
That  on  the  outside,  which  covers  the  adductor  and  flexor  of  the  little  toe,  it> 
next  in  size.  The  internal  portion,  which  covers  the  adductor  of  the  great 
toe,  is  the  smallest. 

The  edges  of  these  portions  dip  down  so  as  to  separate  the  muscles  they  cover 
from  each  other.  They  are  divided  into  five  processes,  corresponding  with 
the  heads  of  the  metatarsal  bones ;  each  of  these  portions  is  divided  into  two 
bands,  which  are  inserted  into  each  side  of  the  head  of  each  metatarsal  bone, 
and  the  tendons,  nerves,  and  arteries  pass  between  them. 

Immediately  under  the  middle  portion  of  this  aponeurosis  are  the  common  short 
flexors  of  the  toes,  viz. 

1.  Flexor  Brevis  Digitorum  Pedis  Sublimis  Perforatus, 

Arises,  by  a  narrow  fleshy  beginning,  from  the  inferior  and 
posterior  part  of  the  protuberance  of  the  os  calcis,  between 
the  adductors  of  the  great  and  little  toes,  soon  forms  a  thick 


392 


MUSCLES  ON  THE  SOLE  OF  THE  FOOT. 


Fig.   105.* 


fleshy  belly,  which  sends  off  four  tendons  that  split  for  the  pas- 
sage of  the  flexor  longus. 

Inserted  into  the  second  phalanx  of 
the  four  lesser  toes.  The  tendon  of  the 
little  toe  is  often  wanting. 

Use.  To  bend  the  second  joint  of  the 
toes, 

2.  Flexor  Digitorum  Accessorim,  seu, 
Massa  Carnea  Jacobii  Sylvii, 

Arises,  by  a  thin  fleshy  origin,  from 
most  part  of  the  sinuosity  at  the  in- 
side of  the  os  calcis,  which  is  continued 
forwards,  for  some  space  on  the  same 
bone  ;  also,  by  a  thin  tendinous  begin- 
ning, from  before  the  tnberosity  of  the 
os  calcis,  externally,  and,  soon  becom- 
ing all  fleshy,  is 

Inserted   into   the    tendon    of     the 
flexor  longus,  just  at   its   division  into 
four  tendons. 
Use.    To  assist  the  flexor  longus. 

3.    Lumbricales  Pcdis, 

Arises,  by  four  tendinous  and  fleshy  beginnings,  from  the 
tendon  of  the  flexor  profundus,  just  before  its  division,  near 
the  insertion  of  the  massa  carnea. 

Inserted,  by  four  slender  tendons,  into  the  inside  of  the  first 
joint  of  the  four  lesser  toes,  and  are  lost  in  the  tendinous  ex- 
pansion that  is  sent  from  the  extensors  to  cover  the  upper  part 
of  the  toes. 


*  The  first  layer  of  muscles  in  the  sole  of  the  foot :  this  layer  is  exposed  by 
the  removal  of  the  plantar  fascia.  1.  The  os  calcis.  2.  The  posterior  part  of 
the  plantar  fascia  divided  transversely.  3.  The  abductor  pollicis.  4.  The  ab- 
ductor minimi  digiti.  5.  The  flexor  brevis  digitorum.  6.  The  tendon  of  the 
flexor  longus  pollicis  muscle.  7,  7.  The  lumbricales.  On  the  second  and  third 
toes,  the  tendons  of  the  flexor  longus  digitorum  are  seen  passing  through  the 
bifurcation  of  the  tendons  of  the  flexor  brevis  digitorum. 


MUSCLES  ON  THE   SOLE  OF  THE  FOOT.  393 

Use.  To  increase  the  flexion  of  the  toes,  and  to  draw  them 
inwards. 

On  the  inside  of  the  foot,  and  under  the  common  flexors,  are 
the  muscles  which  are  considered  as  exclusively  appropriated 
to  the  great  toe,  viz. 


1.  Abductor  Pollicis 

Arises,  from  the  internal  side  of  the  tuberosity  of  the  os 
calcis,  and  from  a  ligament  which  extends  from  this  tuberosity 
to  the  sheath  of  the  tendon  of  the  tibialis  posticus  muscle,  and 
also  from  the  internal  and  inferior  side  of  the  os  navicu- 
lare  and  cuneiforme  internurn.  It  likewise  arises  from  that 
portion  of  the  aponeurosis  plantaris,  which  separates  it  from 
the  short  flexor  of  the  toes,  and  many  of  its  fibres  appear  to  be 
connected  with  the  ligaments  which  pass  from  the  posterior  to 
the  anterior  bones  of  the  foot  :  as  it  passes  under  the  cuneiform 
bone,  a  portion  of  its  lower  surface  is  tendinous. 

It  is  inseparably  connected  to  the  flexor  of  the  great  toe,  and 
is  inserted  into  the  internal  sesamoid  ••  bone,  and  the  inferior 
and  internal  part  of  the  root  of  the  first  bones  of  the  great  toe. 

This  muscle  not  only  separates  the  great  toe  from  the  other 
toes,  but  it  must  increase  the  curvature,  or  arched  form  of  the 
foot. 

2.  Flexor  Brevis  Pollicis  Pedis,  « 

Arises  ,  tendinous,  from  the  under  and  forepart  of  the  os 
calcis,  where  it  joins  with  the  os  cuboides,  from  the  os  cunei- 
forme externum,  and  is  inseparably  united  with  the  abductor 
and  adductor  pollicis. 

Inserted,  into  the  internal  and  external  sesamoid  bones,  along 
with  the  abductor  and  adductor  pollicis,  and  into  the  root  of 
the  first  joint  of  the  great  toe. 

Use.    To  bend  the  first  joint. 

3.  Adductor  Pollicis  Pedis, 

Arises,  by  a  long  thin  tendon,  from  the  os  calcis,  from  the 
os  cuboides,  from  the  os  cuneiforme  externum,  and  from  the 
root  of  the  metatarsal  bone  of  the  second  toe. 


394 


MUSCLES  ON  THE  SOLE  OF  THE  FOOT. 


Fig.  106.*  Inserted  into  the  external  os  sesa- 

moideum,  and  root  of  the  inetatarsal 
bone  of  the  great  toe. 

Use.  To  bring  this  toe  nearer  the 
rest. 

Near  the  outer  edge  of  the  foot, 
under  the  second  portion  of  the  aponeu- 
rosis  plantaris,  are  the  muscles  pecu- 
liar to  the  little  toe,  viz. 

1.  Adductor  Minimi  Digiti  Pedis. 

Arises,  tendinous  and  fleshy,  from 
the  semicircular  edge  of  a  cavity  on 
the  inferior  part  of  the  protuberance  of 
the  os  calcis,  and  from  the  root  of  the 
metatarsal  bone  of  the  little  toe. 

Inserted  into  the  root  of  the   first 
joint  of  the  little  toe  externally. 
Use.    To  draw  the  liyle  toe  outwards  from  the  rest,  and  assist 
in  preserving  the  arched  form  of  the  foot. 


2.  Flexor  Brevis  Minimi  Digiti  Pedis, 

Arises,  tendinous,  from  the  os  cuboides,  near  the  sulcus 
or  furrow  for  lodging  the  tendon  of  the  peroneus  longus  ; 
fleshy  from  the  outside  of  the  metatarsal  bone  that  sustains  the 
little  toe,  below  its  protuberant  part. 

Inserted,  into  the  anterior  extremity  of  the  metatarsal  bone, 
and  root  of  the  first  joint  of  this  toe. 

Use.    To  bend  this  toe. 


*  The  third  and  a  part  of  the  second  layer  of  muscles  of  the  sole  of  the  foot.  1. 
The  divided  edge  of  the  plantar  fascia.  2.  The  musculus  accessorius.  3.  The 
tendon  of  the  flexor  longus  digitorum,  previously  to  its  division.  4.  The  ten- 
don of  the  flexor  longus  pollicis.  5.  The  flexor  brevis  pollicis.  6.  The  ad- 
ductor pollicis.  7.  The  flexor  brevis  minimi  digiti.  8.  The  transversus  pedis. 
9.  Interossei  muscles,  plantar  and  dorsal.  10.  A  convex  ridge  formed  by  the 
tendon  of  the  peroneus  longus  muscle  in  its  oblique  course  across  the  foot. 


INTEROSSEOUS    MUSCLES.  395 

Between  the  metatarsal  bones  are  four  external  and  three  internal  interossei : 
and  one  muscle  which  is  common  to  all  the  metatarsal  bones. 

Interossei  Pedis  Externi,  Bicipites. 

1.  Abductor  Indicis  Pedis , 

Arises,  tendinous  and  fleshy,  by  two  origins,  from  the  root 
of  the  inside  of  the  metatarsal  bone  of  the  fore  toe,  from  the 
outside  of  the  root  of  the  metatarsal  bone  of  the  great  toe,  and 
from  the  os  cuneiforme  internum. 

Inserted,  tendinous,  into  the  inside  of  the  root  of  the  first 
joint  of  the  fore  toe. 

Use.  To  pull  the  fore  toe  inwards  from  the  rest  of  the  small 
toes. 

2.  Adductor  Indicis  Pedis, 

Arises,  tendinous  and  fleshy,  from  the  roots  of  the  metatarsal 
bones  of  the  fore  and  second  toe. 

Inserted,  tendinous,  into  the  outside  of  the  root  of  the  first 
joint  of  the  fore  toe. 

Use.    To  pull  the  fore  toe  outwards  towards  the  rest. 

3.  Adductor  Medii  Digiti  Pedis, 

Arises,  tendinous  and  fleshy,  from  the  roots  of  the  metatarsal 
bones  of  the  second  and  third  toes. 

Inserted,  tendinous,  into  the  outside  of  the  root  of  the  first 
joint  of  the  second  toe. 

Use.   To  pull  the  second  toe  outwards. 

4.  Adductor  Tertii  Digiti  Pedis, 

Arises,  tendinous  and  fleshy,  from  the  roots  of  the  metatarsal 
bones  of  the  third  and  little  toe. 

Inserted,  tendinous,  into  the  outside  of  the  root  of  the  first 
joint  of  the  third  toe. 

Use.   To  pull  the  third  toe  outwards. 


396  INTEROSSEOUS    MUSCLES. 

Interossei  Pedis  Interni, 

1.  Abductor  Medii  Digiti  Pedis, 

Arises,  tendinous  and  fleshy,  from  the  inside  of  the  root  of 
the  metatarsal  bone  of  the  middle  toe  internally. 

Inserted,  tendinous,  into  the  inside  of  the  root  of  the  first 
joint  of  the  middle  toe. 

Use.   To  pull  the  middle  toe  inwards. 

2.  Abductor  Tertii  Digiti  Pedis, 

Arises,  tendinous  and  fleshy,  from  the  inside  and  inferior 
part  of  the  root  of  the  metatarsal  bone  of  the  third  toe. 

Inserted,  tendinous,  into  the  inside  of  the  root  of  the  first 
joint  of  the  third  toe. 

Usl.   To  pull  the  third  toe  inwards. 

3.  Abductor  Minimi  Digiti  Pedis, 

Arises,  tendinous  and  fleshy,  from  the  inside  of  the  root  of 
the  metatarsal  bone  of  the  little  toe. 

Inserted,  tendinous,  into  the  inside  of  the  root  of  the  first 
joint  of  the  little  toe. 

Use.   To  pull  the  little  toe  inwards. 

The  common  muscle, 

Transversalis  Pedis, 

Arises,  tendinous,  from  the  under  part  of  the  anterior 
extremity  of  the  metatarsal  bone  of  the  great  toe,  and  from  the 
internal  os  sesamoideum  of  the  first  joint,  adhering  to  the 
adductor  pollicis. 

Inserted,  tendinous,  into  the  under  and  outer  part  of  the 
anterior  extremity  of  the  metatarsal  bone  of  the  little  toe,  and 
ligament  of  the  next  toe. 

Use,  to  contract  the  foot,  by  bringing  the  great  toe  and  the 
two  outermost  toes  nearer  each  other. 


MOTIONS  OF    THE    SKELETON.  397 


CHAPTER   IX. 

OBSERVATIONS  ON  THE   MOTIONS  OF  THE   SKELETON. 

THE  falling  down  of  the  body  during  life,  when  muscular 
action  is  suspended,  as  well  as  the  examination  of  the  artificial 
skeleton,  evince  that  this  machine  is  not  constructed  to  preserve 
the  erect  position  of  itself;  but  that,  when  unsupported,  it  bends 
at  the  joints,  and  invariably  falls  forward. 

It  is  retained  in  the  erect  position  by  the  action  of  muscles : 
and  that  the  muscles  should  produce  this  effect,  it  is  necessary 
that  they  should  have  a  fixed  basis  to  act  from. 

This  basis  is  the  feet,  and  they  are  fixed  to  the  ground  by 
the  weight  of  the  body. 

To  keep  the  body  from  falling,  it  is  necessary  that  the  centre 
of  gravity  should  be  immediately  over  the  centre  of  the  common 
basis. 

All  our  movements,  both  in  walking,  standing,  and  rising 
from  our  seats,  are  regulated  by  this  principle ;  and  whenever 
we  move  our  body,  so  that  the  centre  of  gravity  is  changed, 
we  must  change  the  position  of  the  feet,  that  the  centre  of  the 
basis  may  be  directly  under  it. 

If  this  proposition  were  not  almost  self-evident,  it  might  be 
illustrated  by  several  very  easy  experiments. 

If  a  person  stand  against  a  wall  with  his  heels  and  the  back 
parts  of  his  legs  and  thighs  in  contact  with  it,  and,  in  this  situa- 
tion, attempts  to  stoop  forward,  he  will  fall  upon  his  face  ;  there 
is  no  power  in  his  muscles,  or  in  any  other  part  of  the  body, 
when  thus  circumstanced,  to  prevent  it ;  but  a  small  movement 
forward  of  one  foot,  will  enable  him  to  stoop  with  ease  by 
altering  the  basis  of  the  body. 

When  we  sit  in  such  a  position  that  we  cannot  bring  the 
centre  of  gravity  over  the  feet,  the  lower  limbs  are  divested  of 
34 


398        ADJUSTMENT  OF  THE  CENTRE  OF  GRAVITY. 

all  power  of  elevating  the  body :  this  is  always  the  case  when 
we  sit  with  the  thighs  and  legs  at  right  angles  with  each  other. 
Bend  the  knees  to  an  acute  angle,  so  that  the  feet  are  placed 
under  the  body,  and  we  rise  with  ease. 

When  we  wish  to  stoop  forward  without  advancing  one  of 
our  feet,  we  acquire  the  power  in  a  small  degree,  by  placing 
our  hands  behind  us,  to  preserve  the  equilibrium. 

Some  old  persons,  whose  spines  curve  forwards  in  conse- 
quence of  age,  bend  their  lower  limbs,  so  that  the  pelvis  may 
be  projected  backwards  beyond  the  centre  of  the  base  of  the 
body,  and  form  a  counterpoise  to  the  upper  part  of  the  trunk. 

Bending  the  knees  alone,  without  projecting  the  pelvis  back- 
wards, will  not  produce  this  effect ;  for  a  person  who  stands 
with  his  back  to  a  wall  will  bend  his  knees  without  obtaining 
this  advantage,  while  the  heels  and  back  part  of  the  pelvis  are 
in  contact  with  the  wall. 

When  we  stand  with  the  toes  pointing  directly  forwards,  the 
base  of  the  body  is  a  square  ;  of  which  the  feet  are  two  of  the 
sides.  As  the  positions  of  the  feet  are  changed,  the  figure  of 
the  base  and  its  centre  necessarily  change  also.  When  the  feet 
are  placed  one  immediately  before  the  other,  the  centre  is  be- 
tween the  toes  of  the  one  and  the  heel  of  the  other.  When 
the  position  of  the  feet  is  such,  that  the  toes  point  directly  out- 
wards, and  the  heels  are  opposite  to  each  other,  the  centre  of 
the  base  is  between  the  heels. 

In  these  cases,  when  the  situation  of  .the  centre  of  the  base  is 
changed,  we  immediately  change  the  centre  of  gravity.  Thus, 
as  we  turn  the  toes  outwards,  the  centre  of  the  base  moves 
backwards,  we,  therefore,  immediately  make  the  body  more 
erect ;  and  by  that  means  keep  the  centre  of  gravity  over  the 
centre  of  the  base. 

We  move  the  centre  of  gravity  laterally,  as  well  as  back- 
wards and  forwards,  in  conformity  to  this  principle. 

Thus,  when  we  raise  one  foot  from  the  ground,  the  body 
inclines  so  much  in  the  opposite  direction,  that  the  centre  of 
gravity  is  directly  over  the  other.  If  the  spine  is  diseased  in 
one  spot,  and  assumes  a  lateral  curvature,  placing  the  centre  of 


ADJUSTMENT  OF  THE  CENTRE  OF  GRAVITY.        399 

gravity  on  one  side  of  the  natural  centre  of  the  base ;  another 
curve  is  formed  by  a  muscular  action,  in  a  sound  part  of  the 
spine,  to  counteract  the  first,  and  keep  the  centre  of  gravity  in 
its  natural  position. 

The  perception  of  a  tendency  to  fall,  when  the  centre  of  grav- 
ity is  in  a  wrong  situation,  first  induces  us  to  make  efforts  to 
resist  this  tendency  ;  we  learn  by  experience  what  these  efforts 
ought  to  be :  and  by  habit  we  at  length  make  them  without 
consciousness. 

As  the  natural  tendency  of  the  skeleton,  when  we  stand,  is 
to  bend  at  the  articulations,  and,  therefore,  to  fall  forwards;  the 
muscles  which  have  the  principal  effort  in  keeping  the  body 
erect,  must  be  the  extensors. 

Thus,  the  muscles  on  the  back  of  the  leg,  and  particularly 
the  soleus,  keep  the  tibia  erect :  while  the  muscles  on  the  front 
of  the  thigh,  the  vasti  and  crureus,  produce  the  same  effect 
upon  the  os  femoris  :  the  bones  being  kept  steady  by  the  occa- 
sional counteraction  of  the  antagonist  muscles. 

The  whole  lower  limb  is  thus  made  erect  by  an  exertion 
which  begins  at  the  foot,  while  the  foot  is  fixed  to  the  ground 
by  the  weight  and  pressure  of  the  body  above  it. 

The  trunk  of  the  body  has  a  strong  tendency  to  bend  for- 
ward at  the  articulations  of  the  thigh  bones  and  the  ossa 
innominata.  This  tendency  is  resisted  by  the  muscles  which 
lie  on  the  back  part  of  the  ossa  femoris,  and  extend  the  trunk 
on  those  bones,  viz.  the  glutei  maximi. 

The  muscles  which  arise  from  the  tuberosity  of  the  ischium, 
and  are  inserted  into  the  leg,  the  semitendinosus,  semimembra- 
nosus,  and  the  long  head  of  the  biceps  flexor  cruris,  have  also 
this  effect. 

The  flexure  of  the  thoracic  and  lumbar  portions  of  the  spine 
is  counteracted  by  the  sacro-lumbalis,  and  longissimus  dorsi, 
which  act  from  the  sacrum  and  back  parts  of  the  pelvis.  The 
yellow  ligaments,  which  are  elastic,  must  also  co-operate  to 
this  effect :  so  that  with  regard  to  the  spine,  there  is  an  additional 
agent  distinct  from  the  muscular  power. 

Indeed,  respecting  the  vertebral  articulations  in  general,  it 


400  MUSCLES  WHICH  KEEP  THE  BODY  ERECT. 

may  be  observed,  that  the  connexion  of  the  bodies  of  the 
vertebrae,  by  the  intervertebral  cartilaginous  matter,  and  of  the 
plates  behind,  by  the  elastic  ligament,  renders  these  articulations 
perfectly  anomalous ;  and  very  different  in  their  principles  from 
the  articulations  in  general. 

In  no  part  of  the  skeleton  is  this  tendency  to  bend  forward 
more  strongly  perceived  thac  in  the  head.  When  we  are 
awake,  and  the  muscles  in  a  healthy  situation,  it  is  effectually 
restrained,  and  the  head  kept  erect,  by  the  splenius  and  corn- 
plexus,  and  other  muscles,  which  act  from  the  spine  below, 
upon  the  back  part  of  the  head  and  the  vertebrae  of  the  neck. 

When  we  stand  on  one  foot,  some  very  different  muscles  are 
called  into  action  ;  the  tendency  of  the  body  is  to  fall  sideways, 
towards  the  foot  which  is  raised  from  the  ground.  To  coun- 
teract this  tendency  the  two  larger  peronei  muscles,  which  are 
situated  on  the  outside  of  the  leg,  act  from  the  foot,  to  keep  the 
leg  erect.  The  vastus  externus  acts  upon  the  same  principle 
from  the  leg  upon  the  os  femoris.  The  gluteus  medius  and 
minimus,  and  the  muscle  of  the  fascia,  act  from  the  os  femoris 
upon  the  pelvis  and  trunk ;  while  the  quadratus  lumborum, 
and  those  abdominal  muscles  which  draw  the  spine  to  that  side, 
continue  the  operation  :  and  so  do  likewise  the  muscles  which 
act  on  the  same  side  of  the  neck  and  head. 

In  rising  from  a  seat,  the  tibialis  anticus  acts  very  powerfully, 
to  keep  the  tibia  erect,  and  prevent  it  from  inclining  backwards. 
The  two  vasti,  and  the  cruraeus,  raise  up  the  os  femoris,  while 
the  gluteus  maximus,  the  sernitendinosus,  and  semimembra- 
nosus,  and  the  long  head  of  the  biceps,  extend  the  trunk  of  the 
body. 

There  are  several  modes  of  walking,  which  are  different  from 
each  other,  in  a  small  degree. 

We  may  walk,  for  example,  with  the  knee  of  the  hind  limb 
straight  or  bent,  as  we  bring  it  forward.  This  circumstance  is 
merely  a  matter  of  accommodation.  But  there  are  two  essential 
processes  in  walking,  viz.  1.  Projecting  one  foot  forward,  and 
placing  it  on  the  ground  while  thus  projected  :  and  2.  Moving 
the  body  over  that  foot. 


MUSCLES  EMPLOYED  IN  RISING  FROM  A  SEAT.  401 

The  mode  of  projecting  the  foot  requires  no  explanation; 
but  the  manner  of  bringing  it  to  the  ground,  when  thus  ad- 
vanced ought  to  be  noticed. 

If,  after  standing  with  both  feet  on  the  same  line,  we  move 
one  foot  forwards,  suppose  the  right  foot,  it  cannot  be  applied 
flat  to  the  ground,  unless  we  either  incline  the  body  forward  or 
move  the  pelvis  on  the  left  thigh,  so  that  the  right  side  may 
present  obliquely  forward  ;  or  lower  the  right  side  of  the  pelvis, 
so  that  it  may  be  nearer  the  ground. 

When  we  incline  the  body  forward,  and  thus  bring  the  right 
foot  to  the  ground,  we  perform  the  second  essential  process  in 
walking,  along  with  the  first :  for  we  move  the  body  over  the 
fore  foot.  The  muscles  on  the  front  part  of  the  hind  leg,  and 
particularly  the  tibialis  anticus,  seem  to  produce  this  effect,  by 
bending,  or  inclining  forward,  the  tibia  on  the  foot. 

When  the  foot  is  brought  to  the  ground  by  a  rotation  of  the 
pelvis,  it  is  likewise  the  tibialis  anticus,  and  the  muscles  on  the 
front  of  the  hind  leg,  that  move  the  body  over  it,  or  that  begin 
the  motion. 

The  gastrocnemius  and  soleus,  and  the  flexors  of  the  toes, 
particularly  that  of  the  great  toe,  occasionally  co-operate  with 
great  effect.  By  raising  the  heel,  and  thus  lengthening  the 
hind  limb,  they  push  the  body  forward,  and  continue  its 
motion  in  that  direction  after  the  effect  of  the  tibialis  anticus 
ceases.  The  length  of  the  step  appears,  therefore,  to  require 
this  elevation  of  the  heel,  and  depression  of  the  toes  ;  but  it 
should  be  observed,  that  when  we  take  long  steps,  we  also  turn 
the  pelvis  partly  round,  presenting  the  side  obliquely  forward ; 
and  in  this  manner  increase  the  anterior  projection  of  the  front  leg. 

Although  the  action  of  the  gastrocnemius,  &c.,  seems  neces- 
sary to  walking  with  long  steps,  we  can  walk  without  their 
operation.  This  is  proved  incontestably  by  the  act  of  walking 
on  the  heel :  when  the  gastrocnemii  and  the  flexors  are  so  far 
from  acting,  that  they  are  in  a  state  of  extension.  In  this  ope- 
ration, the  principal  effort  seems  to  be  made  by  the  tibialis 
anticus,  and  the  muscles  on  the  front  of  the  leg  ;  and  the  exten- 
sor muscles  on  the  front  of  the  thigh. 
34* 


402  MOTIONS  NECESSARY    IN  WALKING. 

Notwithstanding  these  facts,  the  action  of  the  gastrocnemius 
and  soleus  is  essential  whenever  we  raise  the  heel  from  the 
ground,  while  the  weight  of  the  body  presses  on  the  front  part 
of  the  foot ;  and  it  then  acts  with  a  force  which  equals,  if  it 
does  not  exceed,  the  weight  of  the  body. 

Jumping,  at  the  first  view  of  it,  appears  an  extraordinary 
operation ;  but  if  a  man  wh<?  lies  on  the  ground,  with  his  feet 
against  a  wall,  makes  a  muscular  exertion,  such  as  is  necessary 
for  jumping,  the  nature  of  the  operation  is  very  intelligible.  It 
is  a  sudden  extension  of  the  feet  and  knees,  and  sometimes  of 
the  trunk  of  the  body.  The  stroke  is  made  against  the  wall ; 
but  as  that  does  not  yield,  the  whole  motion  is  impressed  upon 
the  body  ;  which  is  projected  from  the  wall  horizontally  in  the 
same  way  that  in  jumping,  it  is  projected  from  the  ground 
vertically. 


PART  IV. 


OF  THE   GENERAL  INTEGUMENTS,  OR  OF  THE   CELLULAR 
MEMBRANE,  AND  THE   SKIN.* 

CHAPTER  X. 

OF  THE   CELLULAR  MEMBRANE. 

THAT  substance  which  is  situated  between  the  skin  and  the 
muscles,  which  is  insinuated  between  the  different  muscles, 
and  between  the  fibres  which  compose  them ;  which  also  con- 
nects the  different  parts  of  the  body  to  each  other,  is  denomi- 
nated the  Cellular  Membrane,  or  Tela  Cellulosa. 

As  it  extends  over  the  whole  of  the  body,  and  is  most  inti- 
mately connected  with  the  skin,  it  is  considered  as  one  of  the 
integuments,  although  it  is  found  in  great  quantities  in  some 
of  the  internal  parts. 

*  The  integuments  of  the  body  consist  of  the  skin  or  dermoid  tissue,  and  of 
that  portion  of  the  common  cellular  tissue  which  is  subcutaneous  and  connects 
the  skin  to  the  subjacent  parts.  The  cellular  tissue  is  loose  and  elastic,  and  by 
its  means  the  skin  is  loosely  connected  to  the  muscles,  and  not  forced  to  follow 
the  muscles  rigidly  in  their  contractions.  In  this  way  the  roundness  of  the  sur- 
face and  the  smoothness  of  the  skin,  is  in  a  great  measure  preserved.  The  skin 
is  directly  continuous  in  the  mouth,  nares,  urethra,  vagina,  anus,  and  external 
auditory  meatus,  with  the  mucous  membranes  lining  the  interior  of  all  the 
cavities  of  the  body.  The  continuation  or  conversion  of  one  into  the  other  at 
these  orifices,  is  so  gradual  as  to  be  almost  insensible,  as  will  be  more  carefully 
shown  under  the  head  of  mucous  membrane.  For  this  reason,  by  many  of 
the  French  anatomists,  the  skin  is  called  the  external  tegumentary  membrane,  and 
the  mucous  membrane  the  internal  tegumentary  membrane.  The  basis  or  derma 
of  the  two  tissues  being  considered  with  some  modification  the  same,  the  cuticle 
analogous  to  the  undried  mucous  of  the  latter  membrane,  the  papilli  and  seba- 
ceous glands  of  the  skin,  to  the  villi  and  follicles  of  the  mucous  tissue. 

This  division  into  two  membranes  is  not  new  ;  it  may  be  traced  to  the  time 
of  Galen,  but  we  are  indebted  for  its  re -introduction  to  science,  principally  to 
Bonn,  and  Bichat.  The  physiological  and  morbid  sympathies  of  the  two  mem- 
branes have  been  long  known,  as  being  more  intimate,  than  that  which  exists 
between  any  two  thoroughly  distinct  tissues  in  the  human  body. — P. 


404  THE  CELLULAR  MEMBRANE. 

It  appears  to  be  composed  of  membranous  laminae,  exqui- 
sitely fine  and  delicate  in  their  structure,  which  are  so  con- 
nected to  each  other  that  they  compose  cells  or  cavities  of 
various  forms  and  sizes. 

When  these  cavities  are  empty,  this  arrangement  of  the  cel- 
lular membrane  is  not  apparent ;  but  when  they  are  distended 
by  water  or  air  it  is  very  evident. 

The  laminae  which  pass  from  one  contiguous  part  to  another 
are  of  different  lengths,  according  to  the  motions  performed  by 
the  different  parts ;  thus,  about  the  muscles  and  their  tendons 
they  are  of  considerable  length,  and  between  the  coats  of  the 
eye  they  are  very  short. 

In  some  places,  these  laminae  are  compressed  together,  and 
form  a  dense  membrane  somewhat  resembling  tendon  ;  but 
whenever  they  are  separated  from  each  other,  they  appear 
pellucid,  and  extremely  delicate. 

The  term  cell  and  cellgerm  being  used  by  the  latest  writers 
on  anatomy  in  a  very  definite  and  restricted  sense,  the  name 
cellular  tissue  seems  to  be  almost  improper  for  a  structure  which 
is  ultimately  composed  of  filaments,  intricately  interwoven,  but 
forming  open  spaces,  and  perfectly  permeable  as  shown  by  the 
easy  transgress  of  fluids  from  one  part  of  the  body  to  another. 
By  cell  is  meant,  a  closed  vesicle,  containing  a  nucleus,  whose 
walls  and  contents  may  undergo  various  changes  by  the  pro- 
cesses of  endosmosis  and  exosmosis,  or  which  may  remain  as  a 
cell  in  the  constitution  of  different  tissues.  These  cells  are  the 
primary  offspring  of  the  cellgerm,  or  cytoblast  (a  nucleus  includ- 
ing a  nucleolus)  being  analogous  to  the  blood  globules  or  corpus- 
cles which  possess  the  faculty  of  producing  their  like,  out  of  the 
surrounding  amorphous  fluid  or  cytoblastema ;  the  vital  fluids 
containing  the  elements  of  all  organic  formation.  Out  of  such  a 
cell-mass,  all  the  organs  in  the  embryo  are  developed,  and  we 
may  still  observe  similar  transformations,  in  the  processes  of  repro- 
duction of  the  different  organs.  Cells,  as  such,  compose  the 
simpler  extra-vascular  tissues,  as  the  adipose  and  pigmentary 
cells,  the  horny  tissue  with  its  various  modifications  in  the  epi- 
dermis, hair,  nails,  horns,  claws,  hoofs,  and  the  epithelium.  In 


THE  CELLULAR  MEMBRANE.  405 

cartilage  and  bone  a  cellular  structure  also  is  visible  as  has  been 
shown  already.  By  their  transformation  into  solid  or  hollow 
fibres,  lamellae  and  membranes,  these  cells  become  the  foijnda- 
tion  of  all  the  other  tissues.  When  cells  pass  into  fibres,  they 
first  become  elongated,  and  generally  in  both  directions ;  their 
walls,  probably  strengthened  by  the  cytoblastema  adhering 
around  them,  become  contiguous,  stretch  themselves  farther, 
and  thus  form  connecting  fibres  between  the  several  nuclei ; 
these  after  having  become  granular,  are  resolved  and  disappear 
altogether,  and  by  interlacings  the  fibrous  structure  is  achieved. 
Out  of  such  cellular  fibres,  the  cellular  tissue  is  composed  ;  they 
are  extremely  fine  and  transparent,  soft  but  tough,  and  appear 
somewhat  contractile,  particularly  in  the  subcutaneous  cellular 
tissue,  which  contain  besides  the  serous  fluid  and  fat  belonging 
to  it,  numerous  vessels  and  nerves,  and  may  be  called  a  main 
laboratory  of  the  animal  chemistry.  The  investing  and  uniting 
cellular  tissue  is  somewhat  firmer  ;  this  covers  the  surface  of  most 
single  organs  and  their  constituent  parts.  Cellular  substance 
enters  also  into  the  composition  of  the  parenchyma  of  the 
organs,  whose  constituent  parts  it  at  the  same  time  unites  and 
isolates. 

—As  the  cellular  tissue  serves  as  the  connecting  medium  of 
other  tissues,  it  might  very  properly  be  called  the  connecting 
tissue.  In  the  fetus,  when  all  the  parts  are  soft,  and  as  yet 
unformed,  it  presents  the  aspect  of  mucus,  filling  up  the  inter- 
stices of  the  other  nascent  organs.  Hence  Bordeu  and  Meckel, 
have  denominated  it  the  mucous  tissue,  and  supposed  that  its 
cellular  and  membranous  structure,  was  produced  mechanically 
by  the  traction  of  surrounding  air,  or  the  infiltration  of  fluid. 
The  term  mucous,  however,  is  inappropriate  and  confusing, 
and  applicable  only  to  the  embryonic  state  of  the  organ  ;  it  has 
been  proved  by  microscopical  investigations  to  be  erroneous 
when  the  development  of  the  tissue  is  complete. 
— The  ultimate  elements  of  all  cellular  tissue  are  fibres,  not 
merely  globules  or  lamellae.  These  primary  fibres  are  among 
the  most  minute  constituent  elements  of  the  human  body. 
Their  diameter,  according  to  the  microscopical  measurements 


406  THE  CELLULAR  MEMBRANE. 

of  Jordon,  is  the  ^th  part  of  an  English  line.  They  are 
transparent,  and  yield  gelatine  on  boiling,  in  which  respect 
they  correspond  with  the  primitive  fibres  of  tendons.  Trevira- 
nus  has  recently  asserted  from  microscopical  observations,  that 
they  are  hollow  cylinders,  which  terminate  by  one  extremity 
in  the  minute  lymphatic  vessels.*  This,  which  possibly  may 
be  the  case,  and  is  supportec^  in  some  measure  the  opinions  of 
Fohman  and  Schwann,  wants  confirmation  from  other  observers.! 
— These  fibres  of  the  cellular  tissue,  are  united  so  as  to  form 
lamellated  membranes  which  cross  each  other  in  all  directions, 
and  produce  an  irregular  interlacement,  constituting  a  series  of 
cells,  which  communicate  together.  The  tissue  thus  formed, 
might  with  propriety  be  called  arealor  or  filamentous.  It  is 
of  a  greyish  aspect  and  highly  elastic.  This  latter  property 
does  not  appear  to  depend  upon  any  innate  elasticity  in  the 
ultimate  filaments,  but  on  the  •  sinuous  disposition  of  these 
filaments,  and  of  the  fasciculi  into  which  they  are  collected.  It 
is  continuous  over  the  whole  body  ;  hence  the  great  extent  to 
which  it  may  be  affected  by  diffuse  inflammation. 
— In  many  parts  of  the  body,  as  in  the  axilla,  under  the  sub- 
scapularis  muscle,  and  between  the  free  surfaces  of  muscles  and 
their  sheaths  the  cellular  tissue  is  very  loose  and  extensible. 
— In  other  situations  it  is  much  more  condensed  and  firm,  as 
in  the  submucous,  subserous,  and  subcutaneous  cellular  tissues. 
— In  the  latter  of  these,  especially  in  that  part  constituting  the 
superficial  fascia,  and  also  in  the  cutis  itself,  it  approaches  to  the 
fibrous  tissues,  both  in  density,  and  in  the  mode  of  arrangement 
of  its  elementary  filaments,  and  is  therefore  not  unfrequently 
named  fibro-cellular  tissue. — 

These  laminae,  when  in  a  healthy  state,  appear  to  have  no 
sensibility  ;  but  so  many  nerves  pass  through  them,  that  pain 
is  generally  felt  when  incisions  are  made  in  the  cellular  mem- 
brane. 

No  vessels  can   be  seen   in  their  composition  when   they  are 


*  Mailer's  Archives  for  1834,  p.  410. 

f  Vide  Breschet,  sur  le  Systeme  Lymphatique,  etc.    Paris,  1836. 


THE  CELLULAR  MEMBRANE.  407 

free  from  disease,  although  many  pass  through  them.  On  this 
account  they  have  been  considered  by  some  very  respectable 
physiologists  as  inorganic  ;  but  there  are  good  reasons  fdf  re- 
garding this  sentiment  as  erroneous. 

If  a  portion  of  cellular  membrane,  in  the  living  subject,  be 
brought  into  view  by  a  surgical  operation  or  a  wound,  and  be 
allowed  to  remain  some  time  covered  by  an  emolient  cataplasm, 
or  a  soft  plaster,  a  complete  change  of  color  will  gradually 
take  place  ;  it  will  become  uniformly  red,  in  consequence  of  the 
great  number  of  minute  vessels  into  which  blood  has  penetra- 
ted during  inflammation ;  and  granulations  will  form  on  its 
surface. 

These  vessels  must  have  existed  previously  in  the  sound 
state  of  the  membrane,  and  conveyed  a  transparent  fluid ; 
although  no  structure  of  this  kind  was  visible.  This  single 
fact  therefore  proves  completely  its  organization. 

In  some  parts  of  the  body,  this  cellular  membrane  appears 
to  be  moistened  by  a  small  quantity  of  tfluid,  or  halitus,  in  its 
cells  ;  which  seems  merely  sufficient  to  keep  it  soft  and  flexi- 
ble. In  other  places  it  is  loaded  with  fat. 

There  is  great  reason  to  believe  that  the  fat  is  contained  in 
cavities  which  are  somewhat  different'  from  the  ordinary  cavi- 
ties of  the  cellular  membrane. 

The  cells  or  cavities  which  contain  the  moisture  or  halitus 
communicate  with  each  other,  over  the  whole  body.  Thus, 
air  insinuated  into  the  cellular  membrane  exterior  to  the  pleura, 
in  consequence  of  a  fractured  rib,  will  be  diffused  over  the 
whole  body  ;  and  produce  the  disease  called  emphysema.  In 
a  patient  who  is  affected  with  that  species  of  dropsy  called 
anasarca,  a  portion  of  the  fluid  will  be  effused  in  the  head  and 
upper  parts  of  the  body,  after  he  has  passed  a  night  in  bed  in 
a  horizontal  position  ;  but  after  he  has  been  in  an  erect  position 
for  some  time,  the  fluid  will  be  accumulated  in  the  legs  and 
feet,  or  most  depending  parts  of  the  body,  in  consequence  of 
its  gravity. 

It  is  well  known  in  dissecting-rooms,  that  the  effused  water 


I 

408  THE  CELLULAR  MEMBRANE. 

may  be  completely  discharged  from  anasarcous  subjects,  by 
making  incisions  in  the  feet  and  placing  the  subject  erect. 

Blood  effused  in  the  cellular  membrane  is  sometimes  dis- 
persed in  the  same  way ;  an  ecchymosis  often  appears  in  the 
eyelids  in  consequence  of  a  contusion  on  the  upper  part  of  the 
head  ;  and  similar  appearances  occur  in  almost  every  part  of 
the  body,  in  consequence  of»effusion  of  blood  at  a  distance  from 
them. 

The  fat  or  adipose  matter  is  not  diffused  in  this  manner  : 
wherever  it  is  first  diffused,  it  remains,  uninfluenced  by  gravi- 
ty, or  the  ordinary  pressure. 

Fat  is  not  observed  in  every  part  of  the  body  ;  it  is  never  seen 
in  the  cellular  membrane  of  the  eyelids  ;  of  the  penis  ;  of  the 
lungs ;  of  the  parts  within  the  cranium  ;  as  well  as  of  several 
other  places.  The  inconvenience  which  would  result  from  the 
accumulation  of  fat  in  these  placer  is  very  obvious  :  and  it  is 
equally  certain  that  the  cellular  membrane  in  them  must  be 
different  from  that  in  which  fat  is  produced. 

From  these  peculiar  circumstances,  relative  to  the  adeps,  it 
has  been  inferred^  that  there  was  a  peculiar  apparatus  for  the 
production  and  retension  of  fat,  superadded  to  the  cellular 
membrane ;  and  some  anatomists,  with  a  view  to  precision, 
have  called  the  part  containing  fat,  Adipose  Membrane,  and 
the  other  part  Reticular  Membrane.*  They  state  that  in  drop- 
sical subjects,  who  are  much  emaciated,  the  membrane  which 
in  a  healthy  state  contained  adeps,  is  more  ligamentous  than 
the  ordinary  cellular  membrane. 

It  seems  to  be  proved,  by  reasoning,  that  there  must  be  a 
considerable  difference  between  these  different  parts  of  the 
cellular  membrane :  but  it  ought  to  be  observed  that  those  parts 
of  the  omentum  which  are  especially  appropriated  to  the 
production  of  adeps,  do  not  exhibit  any  peculiarity  of  structure. 

This  adipose  substance  is  distributed  in  unequal  proportions 
in  different  parts  of  the  body.  In  corpulent  persons  there  is  a 

*  See  remarks  on  the  cellular  membrane,  &c.,  by  Dr.  W.  Hunter,  in  the 
London  Medical  Observations  and  Inquiries,  vol.  ii, 


ADIPOSE    TISSUE. 


409 


considerable  quantity   of  it,  immediately   under  the  skin,  and 
especially  under  the  skin  of  the  abdomen. 

It  is  also  between  the  muscles,  in  the  orbits  of  the  eyes ;  in 
the  omentum  and  mesentery  ;  in  the  joints  and  the  bones  ;  as 
well  as  about  the  kidneys,  and  heart  also,  in  elderly  persons. 
In  the  foetus,  and  for  some  time  after  birth,  it  appears  to  be 
confined  to  the  parts  immediately  under  the  skin,  but  it  soon 
becomes  more  diffused.  — The  fat  in  the  adipose  tissue,  is 
unorganized,  and  at  the  common  temperature  of  the  human 
body,  is  almost  fluid.  On  the  latter  account  it  produces  that 
softness  and  smoothness  of  the  exterior,  particularly  obvious  in 
obese  individuals.  Its  use,  probably,  besides  contributing  to 
the  roundness  and  softness  of  the  exterior,  is  in  part  to  protect 
the  body  against  the  extremities  of  heat  and  cold,  in  conse- 
quence of  its  being  a  bad  conductor  of  caloric.  It  may  be 
considered  also,  as  a  deposit  of  nutriment  held  in  reserve,  to  be 
dissolved  and  taken  up  again  by  the  absorbents,  in  a  protracted 
fast,  or  when  any  wasting  disease  has  impaired  the  functions  of 
nutrition.  Adipose  tissue,  belongs  to  the  most  simple  structures 
of  the  body.  It  differs  from  cellular  tissue  even  to  the  knife 
and  eye,  by  the  toughness  and  coarseness  of  its  web,  and  con- 
sists of  completely  closed  membranous  cells  containing  the  more 
or  less  fluid  fatty  matter.  They  are  affixed  according  to  Mas- 
cagni,  each  one  to  an  artery  and  vein,  the  branches  of  these  ves- 
sels by  which  the  fat  is  deposited,  being  distributed  around  the 
cell.  The  fat  after  being  deposited  in  the  cells  becomes  more 
consistent  by  absorption  ;  it  is  kept  moist  by  a  serous  secretion 
from  the  walls  of  the  cell,  which  effectually  prevents  its  transu- 
dation  into  the  neighboring  tissues.  If  the  fat  be  reabsorbed, 
the  cells  which  have  no  communication  with  each  other,  col- 
lapse and  vanish.  The  diameter  of  these  vesicles  or  cells,  in 
man,  vary  from  T£g  to  ^  of  a  line ;  in  some  places  as  in  the 
spinal  marrow,  they  are  still  smaller — from  the  ^  to  ^  part 
of  a  line.  In  our  larger  domestic  animals,  they  are  of  much 
coarser  structure. — 

It  is  observed  by  dissectors  that  there  are  no  subjects,  how- 
35 


410  CELLULAR  TISSUE. 

ever  emaciated,  who  are  entirely  free  from  fat ;  except  those 
who  have  been  affected  with  anasarca. 

The  cellular  membrane  has  been  already  observed  to  form 
granulations  very  promptly  ;  and  it  has  been  asserted  that  the 
granulations,  which  arise  from  all  the  different  parts  of  the 
body  when  wounded,  originate  from  the  cellular  membrane  in 
those  parts. 

Whether  this  proposition  be  true  or  not,  to  the  extent  abo've 
stated,  it  is  a  fact  that  granulations,  in  some  instances,  seem  to 
have  a  cellular  structure ;  as  the  following  case  will  prove. 

A  patient,  with  a  compound  fracture  of  the  leg,  which  was 
attended  with  a  large  wound,  covered  with  luxuriant  granula- 
tions, was  attacked  with  an  oedematous  swelling  of  the  limb, 
which  increased  suddenly  to  a  great  degree.  While  this  was 
going  on,  the  granulations  on  the  surface  of  the  wound  tume- 
fied with  the  limb  ;  and,  upon  examination,  appeared  some- 
what pellucid,  with  an  effused  fluid  indenting  by  pressure, 
precisely  as  the  skin  was  indented. 

The  cellular  membrane  appears  to  have  a  most  intimate 
connexion  with  the  skin  ;  and  cannot  be  completely  separated 
from  it  by  dissection.  It  is  said  that  in  certain  cases  of  disease 
where  it  is  reduced  to  a  slough,  while  the  texture  of  the  skin 
remains  unchanged,  as  in  some  species  of  anthrax  or  carbuncle, 
this  separation  may  be  completely  effected.  In  such  cases  the 
under  surface  of  the  skin  will  appear  to  be  composed  of  pits 
or  excavations,  which  penetrate  very  deep  into  its  substance, 
and  which  were  occupied  by  the  cellular  or  adipose  membrane 
while  it  was  in  its  natural  condition. 


THE    SKIN.  411 


CHAPTER   XL 

OF  THE   SKIN. 

The  skin  is  composed  of  three  dissimilar  lamina,  which  are  denominated  the 
Cutis  Vera,  the  Rete  Mucosum,  and  the  Cuticula. 

Of  the   Cutis  Vera. 

THE  innermost  of  the  above-mentioned  lamina  is  much  more 
substantial  than  the  others,  and  therefore  is  called  Cutis  Vera. 

It  is  an  elastic,  dense,  and  strong  membrane  ;  which  contains 
in  its  texture  a  large  proportion  of  fibres  that  appear  to  be 
tendinous,  and  are  woven  together  in  an  intricate  manner.* 

Blended  with  these  fibres  is  an  immense  number  of  vessels 
which  enter  into  the  texture  of  the  skin  ;  these  vessels  do  not 
generally  convey  red  blood,  and  therefore  they  are  not  very 
visible  ;  yet  they  may  be  readily  brought  into  view,  by  the 
application  of  rubefacients  during  life  ;  and  by  fine  injections,  in 
the  dead  subject.  Their  existence  is  also  demonstrated  in  the 
vigorous  infant,  at  birth,  by  the  universal  redness  of  the  skin, 
which  is  observable  at  that  time. 

Nerves  are  also  distributed  to  every  part  of  the  skin.  They 
can  be  traced  to  it  very  easily  ;  and  as  there  is  no  part  of  the 
skin  into  which  the  finest  needle  can  be  pushed  without  pain, 
it  is  certain  that  their  distribution  must  extend  to  every  part. 

It  is  highly  probable  that  the  processes  of  absorption  and 
exhalation  are  effected  by  small  vessels  which  originate  or 
terminate  on  the  surface  of  the  skin,  and  of  course  form  a  part 
of  its  texture. 

*  These  fibres  hold  a  middle  station  between  ligamentous  and  common  cel- 
lular tissue,  and  are  supposed  to  consist  of  the  latter  in  a  very  compacted  state. 
The  innermost  layer  of  fibres  is  of  a  reddish  hue,  and  belongs  to  the  class  of 
contractile  tissues.  It  is  to  the  presence  of  this  red  fibro-cellular  tissue,  that  the 
shrinking  and  wrinkling  of  the  skin,  called  goose  flesh  (cutis  anservia)  is  due. 
The  meshes,  which  the  fibres  of  the  skin  leave  when  woven  together,  allow  of 
the  introduction  of  vessels  and  nerves  to  the  papillae  on  the  outer  surfaces  of 
the  cutis  vera.— p. 


412  CUTIS    VERA. 

The  skin,  thus  constructed,  extends  over  the  whole  of  the 
body,  and  is  continued  into  those  cavities  which  open  upon  the 
surface,  as  the  mouth,  nose,  &c.,  although  its  texture  changes 
immediately  upon  its  reflection. 

It  varies  in  thickness  in  different  parts ;  thus,  it  is  thicker  on 
the  back  than  the  front  of  the  body.  It  is  thin  on  the  insides 
of  the  arms  and  leg,  where  opposite  surfaces  touch  each  other.* 

It  is,  in  general,  thinner  in  women  than  in  men. 

The  elasticity  of  the  skin  is  made  evident  by  its  yielding  to 
distention,  and  returning  to  its  usual  size  ;  as  in  pregnancy, 
dropsy,  &c. ;  but  it  is  particularly  demonstrated  in  some  cases 
of  parturition,  when  the  skin  of  the  perinaeum  stretches  im- 
mensely, and,  after  labor,  very  quickly  recovers  its  size. 

The  external  surface  of  the  skin  is  very  generally  divided 
by  superficial  grooves  or  sulci,  into  small  spaces  of  various 
angular  forms  ;  most  commonly  rhomboidal.  On  the  palms  of 
the  hands  and  soles  of  the  feet,  instead  of  these  figures,  we 
perceive  the  whole  surface  composed  of  furrows  and  ridges? 
which,  in  some  places,  are  rectilineal,  and,  in  others,  oval  and 
spiral. 

There  are  also  a  number  of  depressions  or  grooves  which 
seem  formed  to  accommodate  the  various  articulations,  particu- 
larly about  the  fingers  and  toes. 

There  are  other  furrows,  occasioned  by  muscles,  as  those  on 
the  forehead  ;  and  some  depend  on  the  subjacent  cellular  mem- 
brane. 

On  the  external  surface  of  the  true  skin,  when  the  two 
exterior  laminae  are  removed,  many  papillae  are  to  be  seen. 
They  differ  in  size  in  different  parts  of  the  body ;  they  are 
vascular,  and,  on  the  ends  of  the  fingers,  appear  like  villi,  when 
examined  by  a  magnifying  glass. 

There  are  many  perforations  or  pores  to  be  seen  on  the  skin 
with  the  naked  eye,  which  are  probably  the  ducts  of  sebaceous 
glands,  and  the  passages  which  transmit  hairs.  Other  pores, 
different  from  either  of  these,  are  to  be  seen  when  magnifying 
glasses  are  used  ;  as  those  on  the  fingers ;  these  probably  are 

*  The  thickness  on  the  back,  is  about  double  what  it  is  on  the  front  of  the 
body.— p. 


SEBACEOUS     FOLLICLES.  413 

the  exhaling  or  absorbing  pores,  but  their  connexion  with  the 
vessels  which  perform  these  functions  has  not  yet  been  demon- 
strated. ./ 

The  internal  surface  of  the  skin,  when  carefully  dissected 
from  the  subjacent  cellular  membrane,  in  a  subject  of  ordinary 
corpulency,  appears  to  have  some  adipose  substance  in  its 
texture  ;  but,  as  has  been  already  mentioned,  when  the  cellular 
membrane  is  destroyed,  these  portions  of  adipose  matter 
disappear,  and  the  surface  of  the  skin  appears  pitted.  It  is 
probable  that  this  connexion  of  the  cellular  membrane  and  skin 
may  occasion  that  delicacy  of  skin  which  appears  in  some 
hydropic  patients. 

In  some  places  on  the  under  surface  of  the  skin  are  small 
glands  called  miliary,  from  their  resemblance  to  the  millet  seed ; 
these  glands  are  supposed  to  secrete  a  sebaceous  matter,  but 
they  are  not  so  general  as  has  been  supposed. 

They  are  sebaceous  follicles  or  ducts,  which  open  on  the 
external  surface  of  the  skin,  and  contain  an  oily  substance, 
which,  sometimes,  has  the  consistence  of  suet  or  tallow  ;  when- 
these  ducts  are  filled  with  sebaceous  matter,  their  orifices  are 
often  covered  by  a  black  substance,  which  accidentally  adheres 
to  the  surface  of  the  matter,  and  forms  very  small  black  spots 
in  the  skin.  These  often  occur  on  the  nose  and  ears,  and  may 
be  removed  by  pressing  out  the  sebaceous  substance,  which 
rises  up  in  the  form  of  small  worms.  Sometimes  this  secretion 
accumulates  in  the  ducts  in  such  quantities,  that  it  forms  small 
tumors  in  the  skin. 

Fig.  107.  — Fig.  107,  is  a  portion  of  skin  cut  vertically 
from  the  nose  of  an  old  man,  in  order  to  show 
the  sebaceous  follicles  and  their  ducts,  which  are 
magnified  much  beyond  their  natural  size.  They  are  found  in 
all  parts  of  the  body,  with  the  exception  of  the  palms  of  the 
hands  and  soles  of  the  feet ;  but  in  many  parts  only  become 
visible  to  the  naked  eye,  in  diseased  conditions  of  the  skin. 
They  are  most  numerous  in  the  face,  behind  the  ears,  and  in 
the  arm-pits  and  groin.  There  is  a  strong  analogy  between 
them  and  the  follicles  of  mucous  membranes. 
35* 


414 


SEBACEOUS    FOLLICLES. 


Fig.  108.  — Fig.  108,  represents  the  orifices  of  the 

sebaceous  glands,  as  they  are  seen  in 
the  nose,  after  it  has  been  deprived  of 
its  epidermis.  Each  follicle  consists 
of  a  depression  or  doubling  in- 
wards of  the  cutis  vera,  which  be- 
cornjes  more  vascular  and  thin  where 
it  forms  the  walls  of  the  follicle.  The 
sebaceous  follicles,  according  to  E. 
Weber,  are  much  larger  than  and  en- 
tirely distinct  from  those  forming  the 
bulbs  of  the  hairs.  The  latter,  too, 
are  situated  more  deeply,  being  often 
found  in  the  subcutaneous  cellular 
tissue.  They  differ  also,  according  to  him,  in  their  structure  ; 
each  sebaceous  follicle  being  composed  of  four  or  five  com- 
partments or  cells  agglomerated  together.  They  are  also 
larger  than  those  of  the  bulbs  of  the  hairs ;  the  largest  diameter 
of  a  sebaceous  gland,  (the  transverse,)  observed  by  Dr.  Weber, 
was  three-fourths  of  a  line. — 

Muscular  fibres  have  been  supposed  by  some  persons  to 
exist  in  the  skin,  but  such  fibres  have  never  been  demonstrated 
in  it.  The  skin  of  the  scrotum  is  often  much  contracted,  but 
the  fibres  which  produce  this  effect  are  very  visible  in  the 
cellular  membrane,  and  have  a  muscular  appearance. 

Although  the  skin  is  not  muscular,  it  sometimes  changes  its 
appearance  in  a  surprising  manner. 

When  the  surface  of  the  body  is  suddenly  exposed  to  cold, 
or  when  the  chill  of  fever  exists  to  a  considerable  degree,  the 
skin  will  contract  very  sensibly,  and,  at  the  same  time,  a  great 
number  of  conical  papillae  will  project  from  its  surface.  This 
constitutes  the  Cutis  Anserini ;  and  is  supposed  to  be  produced 
by  a  sudden  contraction  of  the  vessels  in  the  skin,  which  forces 
out  their  contents,  and  of  course,  diminishes  its  bulk  ;  while  the 
papillae  do  not  contract  in  the  same  degree,  and,  therefore,  are 
somewhat  projected.  Vide,  article,  contractile  tissue. 

When  the  skin  is  free  from  disease,  the  two  exterior  laminae, 


RETE    MUCOSUM.  415 

(Cuticula  and  Rete  Mucosum,)  may  be  separated  from  it  com- 
pletely, after  maceration  or  putrefaction,  and  the  surface  will 
appear  smooth  ;  but,  in  an  inflamed  skin,  a  net-work  of  vessels 
has  been  injected,  which  is  considered,  by  Mr.  Cruikshank,* 
as  an  additional  lamen.  In  this  lamen,  the  pustules  of  small- 
pox originate.  When  the  skin  is  injected,  they  appear  to  be 
formed  at  first  by  very  small  vessels,  arranged  in  a  radiated 
manner,  with  a  white  uninjected  substance  in  the  centre, 
which  is  supposed  to  be  a  slough,  occasioned  by  the  irritation 
of  the  variolous  matter.  Mr.  Cruikshank,  after  removing  this 
lamella,  was  able,  by  continued  maceration  of  the  same  skin, 
to  separate  another,  which  was  also  vascular.  It  is  to  be 
observed  that  this  skin  had  been  preserved  for  some  time  in 
spirits,  and  was  macerated  in  putrid  water  a  week  during  the 
heat  of  summer,  before  the  first  lamella  was  removed. 

The  color  of  the  healthy  skin  is  invariably  white,  when  all 
the  lamellae  exterior  to  it  are  removed.  This  is  the  case  not 
only  with  the  European,  but  with  the  blackest  African,  and  the 
people  of  all  the  intermediate  colors. 

The  variety  of  colors  in  the  human  species  depends  upon  the 
lamella  next  to  the  cutis,  which  is  now  to  be  described. 

Of  the  Rete  Mucosum. 

Immediately  in  contact  with  the  external  surface  of  the  cutis 
vera  is  a  thin  stratum,  of  a  pulpy  or  mucilaginous  consistence, 
which  appears  to  be  spread  uniformly  over  it,  but  cannot  be 
detached  without  deranging  its  own  texture.f 

It  can  be  best  examined  after  the  cuticle  is  raised  in  a  blister. 
In  this  case  it  appears  like  a  pulpy  substance,  spread  upon  a 
membrane  of  a  soft  and  delicate  texture.  This  is  the  Rete  or 
Corpus  Mucosum. 

In  this  pulpy  substance  resides  the  pigmentum  or  coloring 
matter,  which  gives  the  peculiar  complexion  to  the  different 
races  of  men.  The  cutis  vera  is  white,  and  the  cuticle  is  nearly 
transparent  in  them  all ;  but  this  substance  is  black  in  the  negro ; 

*  See  Experiment  on  Insensible  Perspiration,  &c.  by  "W".  Cruikshank. 
f  It  has  been  asserted  that  the  rete  mucosum  of  the  scrotum  can  sometimes 
be  exhibited  in  a  separate  state. 


416  RETE    MUCOSUM. 

copper-colored,  yellow,  or  tawny,  in  many  of  the  Asiatics ;  and 
yollow,  with  a  tincture  of  red,  in  the  aborigines  of  America  ; 
while  it  is  transparent,  or  whitish,  in  the  people  of  Europe  and 
their  descendants. 

It  can  therefore  be  best  examined  in  the  negroes  ;  and  if  it 
be  inspected  immediately  after  the  cuticle  of  a  blister  is  removed, 
it  will  appear  as  above  described,  with  a  black  matter  diffused 
through  it. 

The  particular  structure  of  this  substance  has  not  been  ascer- 
tained, although  anatomists  have  paid  a  good  deal  of  attention 
to  it.  It  is  generally  believed  by  them  that  no  vessels  can  be 
injected  in  it ;  but  Dr.  Baynham  of  Virginia,  while  he  was 
engaged  in  anatomical  pursuits  in  London,  made  a  preparation 
which  excited  the  attention  of  the  British  anatomists,  on  account 
of  its  particular  relation  to  this  subject. 

He  injected  one  of  the  lower  extremities,  the  os  femoris  of 
which  was  diseased  with  an  exostosis  ;  and  with  a  view  to  an 
examination  of  the  lamina  of  the  skin,  he  removed  a  portion  of 
it  from  the  leg  ;  and  after  immersing  it  a  few  seconds  in  boiling 
water,  to  thicken  the  lamina,  he  macerated  it  in  cold  water  for 
some  days.  Upon  separating  the  cuticle,  after  this  treatment, 
he  discovered  a  texture  of  vessels  on  the  surface  of  the  cutis 
vera,  which  was  distinct  from  the  cutis  itself.  This  has  often 
been  mentioned  as  injection  of  the  rete  mucosum. 

It  is  to  be  regretted  that  Dr.  Baynham,  who  is  particularly- 
qualified  to  decide,  has  pot  published  his  opinion  on  the  sub- 
ject. Mr.  Cruikshank,  to  whom  he  afforded  the  most  satisfac- 
tory opportunity  of  examining  his  preparation,  believes  that 
the  aforesaid  vessels  were  not  a  part  of  the  rete  mucosum  ; 
but  that  the  rete  mucosum  was  to  be  seen  on  the  epidermis, 
(being  raised  with  it  when  it  was  separated  from  the  cutis,) 
while  this  texture  remained  on  the  surface  of  the  cutis.  He 
considers  these  vessels  as  belonging  to  the  additional  lamellae 
already  mentioned,  of  which  he  says  Dr.  Baynham  is  the  dis- 
coverer. 

There  is  therefore  every  reason  to  believe  that  there  is  a 
texture  of  vessels,  either  in  the  ret  3  mucosum,  or  between  the 
cutis  vera  and  the  rete  mucosum. 


CHANGE  OF    COLOR.  417 

After  putrefaction,  or  maceration  for  a  long  time,  the  cuticle 
separates  readily  from  the  cutis  vera  ;  and  the  rete  mueosum 
sometimes  adheres  to  the  skin,  and  sometimes  to  the  cuticle. 
If  the  parts  are  much  softened  by  putrefaction,  the  rete 
mueosum  can  be  washed  away,  like  the  pigmentum  nigrum 
of  the  eye  ;  leaving  the  cutis  white,  and  the  cuticle  nearly 
transparent. 

In  the  negroes  the  black  color  of  the  rete  mueosum  is 
greatly  diminished,  on  the  palms  of  the  hands,  and  soles  of  the 
feet,  and  under  the  nails  ;  but  it  is  perceptible.  It  is  said  that 
the  black  color  does  not  appear  in  the  cicatrices  of  the  blacks. 
This  is  the  fact  with  respect  to  recent  cicatrices ;  but  those  of 
long  standing  are  often  dark-colored,  although  not  so  black 
as  the  original  skin.  The  pits  of  the  small-pox  in  their  skins, 
although  white  at  first,  become  finally  as  dark  as  the  original 
surface. 

In  Europeans  and  their  descendants  the  color  of  the  rete 
mueosum  becomes  darker,  as  they  are  more  exposed  to  the  air 
and  the  rays  of  the  sun  ;  and  soon  changes  again  to  its  original 
fairness,  by  confinement  to  the  house. 

In  negroes  the  skin  loses  some  of  its  deep  glossy  black  color 
during  the  winter  season  of  cold  climates,  and  recovers  it  again 


o 

in  summer. 


The  rete  mueosum  sometimes  undergoes  very  important 
changes ;  there  have  been  several  instances  in  the  United 
States,  where  large  portions  of  the  skin  of  the  African  have 
changed  from  black  to  white ;  owing  probably  to  an  absorption 
of  the  black  pigment  from  the  rete  mueosum  ;  or,  perhaps,  to 
an  absorption  of  the  rete  mueosum  itself. 

There  is  now  in  Philadelphia  a  female,  between  thirty  and 
forty  years  of  age,  in  whom  this  process  is  going  on.  One  of 
her  parents  was  a  negro  and  the  other  a  mulatto  ;  and  her 
original  complexion  accorded  with  her  origin.  But  a  change 
of  color  began  during  her  childhood,  in  small  spots,  which 
have  gradually  increased  so  much,  that  at  this  time  the  whole 
of  her  body  and  limbs  are  nearly  white,  with  the  exception  of 
her  hands  and  feet.  A  large  proportion  of  her  face  is  also  white, 


418  CHANGE  OF    COLOR. 

and  the  remainder  of  it  much  lighter  than  it  was  originally. 
At  this  time,  some  part  of  her  face  has  an  unnatural  whiteness  ; 
but  the  skin  of  her  forearms  appears  like  that  of  a  European  in 
a  perfectly  healthy  state.  This  change  of  color  is  attended 
with  no  unusual  sensation  ;  so  that  if  she  did  not  see  the  altera- 
tion, she  would  not  suspect  that  her  skin  was  any  way  different 
now  from  what  it  had  originally  been.  She  does  not  appear 
sensible  that  the  white  parts  are  more  susceptible  of  irritation 
from  the  rays  of  tbe  sun  than  they  were  originally  ;  but  they 
are  so  mnch  covered  by  her  dress  that  the  experiment  has  not 
yet  been  fairly  made. 

The  first  appearance  of  a  change  is  slight  diminution  of  the 
dark  color ;  this  change  goes  on  gradually,  and  then  small 
spots  appear,  which  are  perfectly  white.  They  gradually 
increase,  and  run  into  each  other,  and  thus  a  large  white  spot 
is  formed. 

In  a  former  case,  where  this  process  had  gone  on  to  a  great 
extent,  it  is  said  that  the  black  pigment  was  again  deposited, 
and  the  skin  resumed  its  original  blackness. 

These  circumstances  in  negroes  have  been  considered  as 
great  deviations  from  the  ordinary  course  of  nature,  but  a 
process  very  analogous  to  it  sometimes  goes  on  in  persons  who 
are  white.  Thus,  there  are  some  in  whom  the  skin  becomes 
much  browner  than  natural  in  some  parts  of  the  body,  parti- 
cularly on  the  arms  ;  and  in  these  brown  portions,  spots  are 
formed  which  are  much  more  white  than  the  natural  color  of 
the  skin. 

In  such  cases  there  appears  to  be  a  deposition  of  coloring 
matter  in  the  rete  mucosum  of  the  brown  places  ;  while  the 
white  spots  are  rendered  more  white  than  natural,  either  by  an 
absorption  of  the  rete  mucosum,  or  by  a  deposition  of  whiter 
matter  in  it. 

The  color  of  the  rete  mucosum  sometimes  undergoes  a 
temporary  change  in  particular  places.  Thus,  at  a  certain 
period  of  pregnancy,  a  dark  circle  forms  round  the  nipple. 

In  some  cases,  where  the  peculiar  whiteness  occurs,  the  skin 
becomes  very  susceptible  of  irritation  from  the  rays  of  the  sun  ; 


ALBINOES.  419 

so  as  to  be  blistered,  if  exposed  to  them  for  a  short  time  ;  this 
circumstance  renders  it  probable  that  the  coloring  matter  in 
the  rete  mucosum  of  the  blacks,  was  originally  designed  to 
protect  their  skins  from  the  very  powerful  rays  of  the  sun  to 
which  they  are  exposed. 

There  are  some  persons  to  be  found,  amongst  most  of  the 
different  races  of  men,  who  are  born  with  this  peculiar  whiteness 
of  the  whole  skin,  which  continues  during  life.  In  these 
persons,  the  hair  has  a  remarkably  white  color,  and  the  eyes 
are  without  the  pigmentum  nigrum.  They  appear  to  be  in  a 
state  of  imperfection,  and  are  unable  to  endure  the  ordinary 
light  of  day.  They  are  generally  designated  by  the  epithet  of 
Albinoes. 

The  texture  which  exists  between  the  cutis  vera  and  the 
epidermis  is  probably  the  principal  seat  of  several  important 
cutaneous  diseases ;  as  the  Scarlatina  Pemphigus,  &tc.*  and 
from  what  has  been  stated,  there  is  good  reason  to  believe 
that  the  small-pox,  also,  commences  in  it.  It  is,  therefore, 
much  to  be  wished  that  its  structure  was  more  precisely  ascer- 
tained. 

— The  variety  of  diseases  which  have  their  seat  in  the  skin, 
as  well  as  the  important  functions  which  it  exercises  in  health, 
have  led  modern  anatomists  to  believe  that  it  was  formed  of 
more  than  the  three  layers  that  Malpighi  assigned  it,  and 
induced  them  to  investigate  its  structure  with  scrupulous  care. 
From  the  innate  difficulties  of  the  subject,  its  anatomy  cannot 
as  yet,  however,  be  considered  as  satisfactorily  made  out,  for 
its  investigators  have  too  frequently  resorted  to  hypothesis, 
when  the  means  of  demonstration  failed  them.  The  doctrines 
of  the  learned  and  judicious  Malpighi,  which  have  been  admi- 
rably detailed  above,  were  generally  admitted  by  anatomists, 


*  In  severe  cases  of  the  scarlatina,  at  the  termination  of  the  disease,  large 
portions  of  the  cuticle  are  sometimes  detached  from  the  cutis,  so  that  several 
practitioners  have  seen  the  whole  cuticle  of  the  hand  come  off  like  a  glove.  As 
the  texture  of  the  cutis  does  not  appear  to  be  altered  in  these  cases,  and  the 
cuticle  is  also  unchanged,  the  cause  of  this  separation  must  exist  in  the  inter- 
vening structure  which  connects  them. 


420  STRUCTURE  OF    THE   SKIN. 

till  M.  Gaultier,*  a  mere  student  of  medicine,  full  of  zeal  and 
candor  published  in  1813  his  researches  on  the  skin,  which, 
though  imperfect  in  some  respects,  went  far  towards  establishing 
its  real  structure. 

— The  rete  mucosum,  which  Malpighi  considered  a  simple 
coating  of  mucous,  between  the  cutis  vera  and  cuticle,  a  sort  of 
varnish  covering  the  papillae,  was  considered  by  Bichat  as 
essentially  formed  of  vessels,  and  divided  by  him  into  two 
vascular  layers,  one  over  the  other,  in  the  outermost  of  which 
was  placed  the  coloring  matter  or  pigment.  But  Gaultier, 
from  his  observation  of  the  skin  of  the  negro,  and  Dutrochet 
from  that  of  quadrupeds,  consider  it  composed  of  many  distinct 
parts.  Gaultier  selected  for  observation  the  skin  of  the  heel  of 
a  negro. where  the  cuticle  is  thickest,  but  which  he  thought 
differed  in  no  other  respect  from  the  skin  in  other  parts  of  the 
body. 

— This  figure  is  a  magnified  representation  of  a  section  of 

the  skin  cut  obliquely  in  regard 
to  its  thickness,  and  transversely 
to  the  lines  formed  by  the 
papillae.  In  this,  according  to 
Gaultier,  we  see  at  1  the  lower 
surface  of  the  derm,  or  cutis  vera.  2,  The  prominences  or  as- 
perities of  the  derm,  forming  the  papillae,  each  one  with  a 
slight  depression  upon  the  top.  3,  Immediately  above  these 
and  continuous  with  them  we  see  a  series  of  vascular  fasci- 
culi surmounting  these  prominences,  called  bloody  pirn- 

*  Gaultier,  whose  opinions  have  been  adopted  in  the  main  by  Beclard,  Blan- 
din,  Cloquet  and  others,  would,  if  he  had  lived,  most  probably  done  much 
towards  simplifying  and  perfecting  his  views.  Appointed  army  surgeon  imme- 
diately after  his  graduation,  he  fell  a  victim  to  the  disasters  of  the  Russian, 
campaign.  The  investigation  has,  however,  been  taken  up  by  Dutrochet  who 
extended  it  to  the  skins  of  quadrupeds,  by  several  of  the  German  and  Italian 
anatomists,  and  lastly  by  Breschet  and  Roussel  de  Vauzeme.  The  last  have 
made  it  a  subject  of  elaborate  microscopical  research,  not  only  in  man,  but  in 
the  whale  and  many  of  the  larger  animals.  The  views  of  Gaultier  thus  modi- 
fied and  improved,  are  well  deserving  of  study  as  the  most  satisfactory  yet 
given,  though,  from  the  doubt  which  is  always  attached  to  microscopical 
observations,  they  must  be  looked  upon  rather  as  the  probable  than  the  proven 
structure. — r. 


ACCORDING    TO  GAULTIER.  421 

Fig.  1 W.*  pies,   (bourgeons  sanguins.)   3,  The  tunica    albida 

§&  profunda,  covering  these  papillae  upon  their  top 
ft  and  sides,  and  united  to  the  upper  surface  of  the 
'  derma,  and  composed  entirely  of  white  vessels, 
(serous  capillaries.)  4,  Gemmules ;  a  sort  of  membrane  so 
named  from  its  undulations,  excavated  on  its  internal  face, 
which  covers  in  the  tunica  albida  profunda.  This  is  the  seat  of 
the  coloring  matter  of  the  skin,  and  each  undulation  receives 
two  of  the  bifid  tops  of  the  papillae,  called  bourgeons  sanguins. 
5,  Tunica  albida  superficialis,  which  covers  over  the  gemmules, 
and  is  also  formed  entirely  of  white  vessels.  6,  The  external  face 
of  the  skin,  which  is  only  the  dried  surface  of  the  tunica  albida 
superficialis,  or  the  proper  epidermis.  Gaultier  considers  four 
of  these  layers  as  belonging  to  the  rete  mucosum  ;  the  perpen- 
dicular vascular  fasciculi  (bourgeons  sanguins,)  the  gemmules 
and  the  two  white  tunics. 

Fig.  lll.f  — The  first  and  second  of  these 

four,  correspond  with  the  two 
vascular  layers  which  Bichat  as- 
signs to  the  rete  mucosum  ;  and 
the  views  of  Gaultier  differ  from 
this  writer's  in  his  adding  two  more  tunics,  tun.  albid.  profun- 
da, and  tun.  albid.  superficialis.  But  the  vascular  fasciculi, 
as  Dutrochet  and  Beclard  have  asserted,  belong  to  the  cutis 
vera,  and  form  a  part  of  the  proper  papillary  body  ;  and  were 
probably  the  parts  injected  by  Baynham  and  Cruikshank — 
thus  leaving  the  rete  mucosum  formed  of  three  layers.  Thus 
modified,  Gaultier's  researches  have  been  adopted  by  many 
writers. 

— But  there  were  not   wanting  others  who  entertained  different 
views.     Gall   believed   the    rete  mucosum    a  nervous  expansion 


*Fig.  110, — Is  a  representation  of  the  skin,  and  the  basis  of  the  papillae, 
the  latter  surmounted  by  the  vascular  villi  or  fasciculi,  (bourgeons  sanguins.) 
The  space  between  these  fasciculi  is  filled  up,  in  the  natural  state  of  the  parts, 
according  to  Gaultier,  with  the  tunica  aibida  profunda. 

f  Fig.  Ill, — Is  a  representation  of  the  derm,  or  cutis  vera,  with  a  line  of 
prominences  on  its  upper  surface,  constituting  the  basis  of  the  papillae. 

36 


422  •        STRUCTURE  OF  THE  SKIN 

for  the  reception  of  tactile  impressions;  an  opinion  purely  hypo- 
thetical and  erroneous  ;  Chaussier,  that  the  skin  was  composed 
of  but  two  parts,  the  dermis  and  epidermis,  and  that 
which  had  been  called  the  rete  mucosum  was  probably  a 
part  of  the  dermis  ;  Blandin,*  that  the  rete  mucosum,  consist- 
ing of  three  layers  according  to  Dutrochet  placed  between  the 
papillary  bodies  and  the  epidermis,  had  neither  vessels  or 
nerves,  was  a  product  of  secretion  from  the  papillae,  like  the 
epidermis,  and  formed  in  fact  a  second  epidermis  thicker  and 
softer  than  the  external,  and  that  it  had  no  more  vitality  than 
the  hair  and  nails. 

— -Breschet  and  Roussel  de  Vauzeme,f  have  in  this  uncertain 
and  imperfect  state  of  our  knowledge,  endeavored  with  the 
aid  of  the  scalpel  and  the  microscope,  to  determine  positively 
its  structure.  Their  researches  have  been  extended  not  only 
to  the  skin  of  man,  but  to  that  of  whales  and  others  of  the 
cetaceae.  The  discoveries  which  they  allege  to  have  made  are 
surprising,  and  though  their  researches  appear  to  have  been 
made  with  much  labor  and  ingenuity,  their  confirmation 
or  overthrow  must  depend  upon  the  investigation  of  others 
equally  familiar  with  the  same  instruments. 
— But  it  must  not  be  forgotten  that  such  high  magnifying 
powers  as  they  have  used,  expose  the  most  wary  and  honest 
observer  to  optical  illusions.  This  cause  led  De  la  Torre,  to 
assert  that  the  globules  of  the  blood  were  annular. 
— According  to  these  writers,  the  skin  consists  of  but  two  layers. 
The  derm,  or  cutis  vera,  and  an  external  layer,  which  they  call 
indifferently  epidermis,  corneous  matter,  corneous  tissue,  or 
epidermic  layers.  This  external  layer  comprises  the  rete  muco- 
sum and  epidermis  of  other  writers,  and  they  consider  it  composed 
of  the  same  substance,  mucus,  in  a  greater  or  less  state  of  desic- 
cation. It  is,  however,  composed  of  many  distinct  parts,  not 
arranged  in  the  form  of  layers.  Fig.  112,  represents  an  imagi- 
nary scheme  or  plan,  in  which  they  have  placed  together  the 

*  See  Anat.  Generale  of  Bichat,  Paris,  1831.— 

f  Nouvelle  recherches  sur  la  structure  de  la  peau,  par  G.  H.  Breschet  and 
Roussel  de  Vauzeme. — Paris,  1835. — 


ACCORDING  TO  BRESCHET  AND  ROUSSEL  DE  VAUZEME.   423 

constituent  parts  of  the  skin,  the  existence  of  which  they  had 
proved  separately  under  the  microscope. 

— Thus,  a  is  the  derm,  b,  The  corneous  or  horny  epiderrmic 
matter,  c,  The  vessels  and  nerves  which  go  out  from  the  der- 
mis.  d,  Space  filled  up  by  their  capillary  branches,  e,  Ner- 

Fig.  112.* 


vous  or  tactile  papillae.  The  diapnogenous,  or  sudoriferous 
apparatus,  composed  of  a  glandular  parenchyma,/,  and  of  spi- 
ral sudoriferous  canals,  g.  The  glandular  or  secretory  organ  is 
inclosed  in  the  substance  of  the  skin,  and  the  canals  pass  up 
between  the  papillae  and  open  obliquely  on  the  surface  of  the 
epidermis,  constituting  the  microscopical  orifices,  from  which 
we  see  the  sweat  exuding  on  the  palms  of  the  hand,  and  soles 
of  the  feet.  A,  The  inhaling  apparatus,  or  absorbent  canals, 
which  resemble  in  many  respects  the  lymphatic  vessels  :  they 
are  situated  in  the  corneous  matter,  or  rete  mucosum ;  they  are 
seen  to  commence  under  the  most  superficial  layer  of  the  corne- 
ous matter  which  forms  the  cuticle  ;  no  mouths  or  orifices  are 
seen,  and  it  is  impossible  to  say,  whether  they  commence  in  the 
form  of  a  cul  de  sac  or  not.  They  pass  down  between  the  papil- 
lae, by  the  side  of  the  sudoriferous  canals,  and  communicate  with 


424  STRUCTURE    OF    THE    SKIN 

a  net- work  of  vessels,  which  they  believe  to  be  lymphatics 
mixed  up  with  veins,  spread  upon  the  surface  of  the  derm.* 
it  The  organs  which  secrete  the  mucus,  of  which  the  rete  mu- 
cosum  and  cuticle  is  formed,  or  blennogenous  apparatus  ;  this 
consists  of  a  glandular  parenchyma  situated  in  the  thickness  of 
the  derm,  and  of  short  excretory  canals  fr,  which  deposit  the 
mucous  matter  between  the  Abases  of  the  papillae.  The  chro- 
matogonous  organs  or  glands,  which  secrete  the  coloring 
matter  or  scales,  run  parallel  with,  and  immediately  below  the 
grooves  on  the  surface,  and  between  the  papilli,  which  they 
are  also  placed  a  little  below.  The  ends  of  them,  marked  by 
a  collection  of  dots,  can  of  course  only  be  seen  in  the  plan,  in 
consequence  of  their  running  parallel  with  the  grooves,  and 
between  the  parallel  ranges  of  papillae. 

— They  consist  of  a  glandular  parenchyma,  receiving  an  abun- 
dance of  capillary  vessels  from  the  derm  below,  and  possessing 
excretory  canals  above,  that  throw  upon  the  surface  of  the 
derm,  the  coloring  principle,  which  is  mixed  with  the  soft  and 
diffluent  corneous  or  mucous  matter,  secreted  by  the  blennog- 
enous apparatus.  From  this  mixture  results  the  pretended 
rete  mucosum  of  Malpighi,  and  the  epidermis  or  cuticle. 
From  this  apparatus  is  also  produced,  they  think,  the  horns, 
scales,  spines,  bristles,  hair,  wool,  hoofs,  nails,  etc.  of  different 
animals.  It  is  solidified  in  successive  couches,  to  the  right  and 
left,  as  seen  in  the  section  across  the  grooves,  /;  but  in  the 
longitudinal  section  m,  these  layers  present  a  series  of  straight 
lines  one  above  another  like  the  leaves  of  a  book. 
—  In  consequence  of  this  arrangement,  the  corneous  matter, 
when  macerated,  throws  off  layer  after  layer.  The  superior 
face  of  the  epidermis  presents  grooves,  as  represented  at  n, 
which  correspond  to  the  interpapillary  grooves  of  the  derm, 
o,  Are  the  prominent  ridges  in  the  cuticle  formed  over  the 
papilla,  separated  by  transverse  grooves,  p,  at  the  bottom  of 
which  are  found  the  pores  of  the  sudoriferous  canals,  e,  Are 


*  The  existence  of  these  inhalent  vessels,  from  some  observations  I  have 
made  with  a  very  powerful  microscope,  I  should  consider  extremely  doubtful. — P. 


ACCORDING  TO  BRESCHET  AND  ROUSSEL  DE  VAUZEME.  425 

the  vessels  and  nerves  which  enter  into,  or  go  out  from  the  derm. 
d,  An  interval  filled  up  by  capillary  filaments. 

Of  the  Derm, 

— The  external  surface  of  the  derm,  is  lined  by  a  very  thin 
adherent  membrane,  which  is  reflected  over  the  tops  of  the 
papillary  bodies  and  forms  their  neurilema.  The  horny  or 
epidermic  matter  is  secreted  in  the  grooves  between  the  papillae, 
and  is  moulded  around  all  the  inequalities,  the  form  of  which  is 
exactly  impressed  on  all  the  layers  of  the  epidermis.  In  serpents, 
the  derm,  has  a  singular  arrangement ;  it  is  elevated  in  imbri- 
cated projections,  covered  by  a  thin  layer  of  epidermis  ;  these 
are  called  scales.  In  fishes,  on  the  contrary,  the  surface  of  the 
derm  is  smooth,  and  the  scales  are  formed  only  of  the  horny 
matter.  The  derm  is  a  membrane,  the  fibres  of  which  are 
solidly  interlaced  together,  with  interstices  for  the  passage  of 
vessels,  nerves  and  canals,  and  in  which  are  lodged  many 
organs,  as  has  been  shown  in  the  plan,  page  423.* 

Of  the  Papillary  Body,  or  JNeurothelic  Apparatus.^ 

— This  consists  of  a  series  of  little  prominences  on  the  upper 
surface  of  the  derm,  the  cleft  at  the  top  into  two  portions,  each  of 
which  is  composed  of  a  bundle  of  nerves  and  vascular  fila- 
ments— the  bourgeons  sanguins  of  Gaultier.  The  form  of  each 
papilla  is  that  of  a  cone.  The  base  is  expanded  in  the  upper 
surface  of  the  derm,  and  its  two  prominences  or  villi,  termi- 
nating in  a  rounded  point,  are  received  in  the  horny  layers  of 
the  epidermis,  like  a  sword  in  its  sheath,  (see  page  426.) 
— The  direction  of  the  papilla  is  slightly  oblique  in  the  epider- 

« 

*  The  method  adopted  by  these  writers  for  microscopical  examination  of  the 
skin,  was  to  take  a  piece  of  recent  skin  in  which  the  vessels  were  distended  by 
cadaveric  accumulation  of  blood,  or  filled  with  injection.  A  portion  from  the 
heel  is  preferable.  This  is  to  be  allowed  partially  to  dry,  and  the  thinnest  pos- 
sible transparent  slice,  cut  off  vertically.  This  is  to  be  placed  upon  a  piece  of 
moistened  glass  and  examined  under  the  microscope  with  the  use  of  a  lamp 
and  reflector.  In  this  way  they  were  able  readily  to  see,  and  isolate  with  curved 
cataract  needles,  all  the  vessels,  nerves  and  glandula  apparatus  of  the  skin.— p. 

f  From  ne.uron,  nerve,  and  thtla,  papilla. — 

36* 


426  STRUCTURE    OF     THE    SKIN 

mic  layers,  as  seen  in  fig.  113.*  The  nerves  are  here  seen 
passing  up  into  the  papillae  through  the  dermis  ;  the  vascular 
branches  which  accompany  them  are  not  here  represented. 
The  papilla  first  gets  a  neurilema/ic  covering  from  the  upper 
surface  of  the  derm,  and  is  there  furnished  with  several  layers 
Fig.  113.f  of  the  epidermic  horny  matter,  which 

cover  it  like  a  hood.  This  horny  cov- 
ering is  particularly  thick  at  the  heel, 
and  serves  to  protect  the  papillae  by  the 
deadening  of  shocks,  and  resisting  the 
pressure  of  the  weight  of  the  body. 
The  papillae  are  most  numerous  on  the 
palms  of  the  hands  and  soles  of  the 
feet,  but  are  also  scattered  over  other 
parts  of  the  body.J 

Of  the  Sudoriferous  or  Diapnogenous 
Apparatus. 

— This  consists  of  a  gland,  see  fig.  112,  p.  423,  placed  in  the 
substance  of  the  dermis,  near  its  inner  surface,  into  which  a 
great  many  capillary  vessels  run,  and  of  a  spiral  duct  which 
runs  up  through  the  horny  layers  and  opens  obliquely  through 
the  outer  epidermic  crust  by  a  slight  depression  or  pore,  on  the 

*  According  to  these  writers  the  nerves,  as  they  pass  up  from  the  under  sur- 
face of  the  skin,  becomes  soft,  flexuous,  and  capillary,  and  as  they  enter  the 
villi  on  the  top  of  the  papilli,  lose  their  neurilema,  and  are  expanded  in  the 
form  of  pulp.  They  look  upon  the  changes  which  the  nerve  undergoes,  and 
upon  the  derm,  villi,  and  epidermic  covering,  as  so  many  parts  necessary  to 
constitute  the  perfect  organ  of  touch  :  thereby  assimilating  it  to  the  more  com- 
plicated organs  of  sight  and  hearing. — Loc.  cit.  p.  15,  et  seq. — 

f  Fig.  113,  represents  the  apparatus  which  constitutes  the  organ  of  touch  in 
man.  a,  Nerve  entering  into  the  dermis,  where  it  becomes  capillary,  b,  Its 
entry  into  the  papilla,  c,  Neurilema  furnished  by  the  dermis.  d,  Proper  envel- 
op of  the  nerve,  e,  Corneus  layers  more  or  less  thick,  which  form  the  organ  of 
protection  to  the  nerve.  The  capillary  blood-vessels  which  pass  up  with  the 
nerves  are  not  here  shown. 

$  From  their  observations  upon  the  papillae  of  the  whale,  these  anatomists 
are  disposed  to  believe  that  the  nervous  fibrils  terminate  at  the  top  of  the  villi, 
by  loops  with  one  another,  as  Prevost  and  Dumas  have  shown  them  to  do  in 
other  parts  of  the  body. — 


ACCORDING    TO    BRESCHET    AND    ROUSSEL    DE    VAUZEME.      427 

back  of  the  epidermic  ridges,  formed  over  the  papillary  bodies. 
These  are  the  orifices  from  which  the  sweat  exudes,  and  may 
be  readily  seen  with  a  single  lens  of  moderate  magnifying 
power,  on  the  palms  of  the  hands,  soles  of  the  feet,  nose,  and 
other  portions  of  the  body.  The  obliquity  of  the  orifice,  gives 
it  a  valvular  arrangement,  like  that  of  the  ureters  where  they 
enter  the  bladder.  In  consequence  of  this  the  valve  closes  the 
orifice,  when  the  epidermis  is  raised  by  cantharides,  and  the 
duct  is  broken  off,  so  that  the  pores  are  not  generally  visible  ; 
this  has  occasioned  some  anatomists,  of  great  reputation,  (J. 
F.  Meckel,  Cruikshank,  Blumenbach,  etc.)*  to  deny  altogether 
the  porosity  of  the  epidermis,  and  to  believe  that  the  sweat 
passed  by  exudation  or  exosmosis  directly  through  its  sub- 
stance. In  carefully  elevating  the  cuticle  from  the  subjacent 
coats,  these  ducts  are  visible  as  very  fine  transparent  elastic 
filaments ;  the  spiral  being  converted  into  straight  tubes  by  the 
traction,  and  which  W.  Hunter,  Bichat,  and  Chaussier,  accord- 
ing to  these  writers,  mistook  for  the  exhalent  and  absorbent 
vessels.f  Others  supposed  they  were  filaments  of  cellular 
tissue,  uniting  the  epidermis  to  the  subjacent  layer.J  The 
sudoriferous  organs,  which  are  exceedingly  numerous,  are 
probably  the  only  exhaling  organs  of  the  skin. 

The  Inhaling  Apparatus. 

— This  is  properly  an  appendage  of  the  absorbent  system  ;  and 
may  be  seen,  according  to  these  anatomists,  with  a  lens  of 
feeble  magnifying  power,  or  even  with  the  naked  eye,  in  rais- 
ing the  epidermis  with  proper  precaution.  They  have  not, 
however,  been  enabled  to  make  out  their  anatomy  satisfactorily. 

*  Beclard  was  disposed  to  consider  these  pores  as  the  orifices  of  the  sebace- 
ous glands,  though  he  expresses  himself  doubtingly  upon  the  subject,  and  says 
that  the  rout  by  which  the  sweat  traverses  the  epidermis  is  entirely  unknown. — p. 

f  The  existence  of  exhalent  vessels,  was  a  mere  presumption  of  Bichat,  and 
has  never  been  demonstrated. — p. 

|  Eichhorn  has  also  observed  these  sudoriferous  canals,  and  his  description 
of  them  corresponds  in' many  respects  with  that  of  Breschet.  (Memoire  sur 
les  exhalations  que  se  font  pour  le  peau,  et  sur  la  voies  par  lesquelles  elles  sont- 
lieu  ;  par  Henri  Eichhorn.)  Arch,  de  Meckel. — p. 


428 


STRUCTURE   OF  THE   SKIN 


They  describe  them,  see  fig.  112,  as  arising  by  isolated  radicles 
from  the  under  part  of  the  grooves  of  the  epidermis,  and  not 
opening  to  the  surface  ;  the  fluids  which  they  take  up  getting 
into  their  cavities  by  previous  imbibition  through  the  outer 
cuticular  covering.  In  passing  downwards  towards  the  derm, 
they  are  in  company  with  the  sudoriferous  ducts,  and  in  the 
substance  of  the  derm,  becomes  continuous  with  the  common 
absorbent  vessels.* 

Fig.    114.f 


Blennogenous  Apparatus, 

— Or  organs  that  produce  the  mucous  substance,  which,  in 
its  first  soft  condition,  forms  the  mucous  body,  heretofore 
known  under  the  name  of  rete  mucosum,  and  which,  hardened 
upon  the  surface  constitutes  the  horny  matter  of  the  epidermis. 

*  The  existence  of  these  absorbent  vessels  immediately  beneath  the  cuticle 
and  on  the  upper  surface  of  the  dermis,  has  been  demonstrated  by  Tiedemann, 
Fohman,  and  Lauth.  Breschet  asserts  the  discovery  of  an  additional  structure, 
in  his  inhaling  apparatus,  arising  in  the  corneous  tissue.— p. 

f  Fig.  114. — a,  Chromatogenous  organ  torn  in  two  places,  b  and  c,  to  show 
the  escape  of  the  scales,  and  the  thread-like  vessels  of  which  this  organ  is 
composed,  d,  Its  small  excretory  canals,  torn  in  removing  the  corneous  mat- 
ter, e,  Blennogenous  or  mucous  gland,  which  throws  its  secretion  above  the 
chromatogenous  organ.  /,  Fluid  state  of  the  corneous  matter,  that  is  to  say, 
pigmentum  or  scales  floating  in  the  midst  of  mucus,  (rete  mucosum  of  Mal- 
pighi.)  £,  Layers  of  corneous  or  horny  matter  stratified  to  the  right  and  left, 
more  and  more  condensed,  the  nearer  they  approach  the  surface.  Into  the 
mucous  gland  is  seen  running  a  sanguineous  vessel,  and  round  it  are  placed  a 
number  of  little  whitish  granules. 


ACCORDING  TO  BRESCHET  AND  ROUSSEL  DE  VAUZEME.  429 

To  see  these  well  with  the  microscope,  it  is  necessary  to  have 
a  piece  of  fresh  skin  well  injected  with  blood.  There  is  then 
to  be  seen  at  the  base  of  the  derm,  little  reddish  glands,  irregu- 
lar on  the  surface  and  grooved  by  blood-vessels.  They  are 
enveloped  in  cellular  membrane  and  surrounded  by  a  multi- 
tude of  minute  adipose  vesicles.  From  the  top  of  each  of  these 
glands  as  seen  in  fig.  114,  passes  up  a  duct,  which  opens  on 
the  upper  surface  of  the  derm  in  the  grooves  between  the  pa- 
pillae. Many  capillary  vessels  adhere  to  the  tube  and  the 
gland,  and  a  vessel  of  considerable  size  enters  the  base  of  the 
latter.  The  mucous  matter  thrown  on  the  surface  of  the  derm 
by  these  organs,  quickly  unites  with  a  coloring  matter,  from 
which  results  the  different  tints  of  the  corneous  or  epidermic 
substance,  hair,  nails,  scales,  feathers,  etc.  in  man  and  other 
animals.  This  coloring  is  formed  by  the 

Cromatogenous*  Apparatus,  (see  Jig.  114,) 

— which  is  placed  at  right  angles  to  the  ducts  of  the  mucous 
glands,  at  the  upper  surface  of  the  derm,  and  at  the  bottom  of 
the  grooves.  Its  structure  is  parenchymatous  or  spongy.  On 
its  under  surface,  it  receives  a  great  number  of  minute  capillary 
vessels,  which  is  the  outer  limit  of  the  vascular  system,  with  the 
exception  of  the  vessels  which  pass  up  into  the  villi.  On  its 
surface  arises  many  short  ducts,  and  which  open  in  the  grooves 
between  the  papillae,  to  convey  up  the  coloring  matter  in  the 
form  of  small  granules  to  mix  with  the  mucus.f  When  this 
tissue  is  torn,  a  great  many  small  filaments  are  seen  (a,)  from 
which  escape  small  scales  or  colorless  corpuscles  in  great 
quantities,  (b,  c.)  This  reservoir  of  scales  is  found  in  no  other 
part  of  the  derm. 

— At/*,  is  seen  the  fluid  state  of  the  corneous  matter — that  is 
to  say,  the  pigment  of  the  scales  floating  in  the  midst  of  the 
mucus.  At  g,  couches  of  this  matter,  hardened  and  stratified, 
to  the  right  and  left  as  they  approach  the  surface,  form  the 

*  From  x/>cj/m,  color,  and  yewau,  to  create. — p. 

f  The  coloring  matter  as  is  very  obvious  in  the  black,  is  now  found  to  be 
deposited  in  delicate  hexahgedral  cells  which  are  called  pigmentary  cells.  In  the 
choroid  coat  of  the  eye  the  cells  are  arranged  in  several  layers  over  each  other, 
so  as  to  form  a  pigmentary  membrane,  the  surface  appearing  perfectly  black. 


430  OF     THE    CUTICLE. 

coverings  of  the  papillae,  and  which  are  thus  secreted  and 
moulded  around  these  organs. 

— The  whole  of  the  corneous  tissue  of  the  skin,  (included 
usually  under  the  terms  of  rete  mucosum  and  epidermis,)  is 
formed  according  to  these  anatomists  of  the  mingled  products 
of  these  mucous  and  coloring  glands.* 

The  Cuticula  or  Epidermis, 

has  been  examined  with  the  greatest  care  by  several  of  the 
most  successful  anatomists ;  but  notwithstanding  their  labors, 
the  structure  of  this  substance  is  by  no  means  understood. 

It  appears  to  have  some  resemblance  to  the  matter  of  the 
nails,  and  of  horn :  but  is  rather  more  flexible,  even  after 
allowing  for  the  difference  in  thickness. 

In  those  parts  where  it  is  thinnest  it  is  semitransparent. 

It  is  insensible,  and  no  vessels  can  be  seen  in  it.f 

*  In  investigating  this  obscure  and  difficult  part  of  anatomy,  it  has  been 
usual  with  observers  to  select  the  skin  of  the  palms  of  the  hands  and  soles  of 
the  feet,  as  a  type  of  the  whole   cutaneous  system.     There  is,  however,  a 
difference  to  be  observed.     In  the  palms  and  soles  resides  pre-eminently  the 
sense  of  touch.     These   parts  are  likewise  destitute  of  hair,  and  the  papillae 
which  are  there  very  numerous  and  visible  to  the  naked  eye.  are  very  sparsely 
distributed  and  appear  rudimental  in  other  parts  of  the  body.    Much  of  the 
discrepancy  among  anatomists  in  regard  to  the  structure  of  the  skin,  appears 
to  be  owing  to  whether  they  have  made  their  researches  mainly  upon  the  palms 
and  soles,  or  upon  the  skin  of  other  parts  of  the  body.     Chevalier*  and  Wallace,! 
have  described  especially  in  the  skin  of  the  face,  arms,  and  legs,  a  system  of 
epidermoid  glands,  seated  in  the  rete  mucosum,  and  so  minute  that  the  latter 
counted  one  hundred  of  them  in  the  one-twenty-fourth  part  of  a  square  inch, 
and  which  gave  issue  to  the  sweat.     These  appear  to  me,  to  correspond  with 
the  diapnogenous  apparatus  of  Breschet,  as  he  represents  them  in  the  palms  and 
soles. 

The  opinion  of  Bichat,  is  therefore  erroneous,  that  the  sense  of  touch  is  only 
more  perfect  in  the  hands  than  other  portions,  in  consequence  of  the  shape  of 
the  parts,  and  the  facility  with  which  they  may  be  applied  round  objects,  and 
that  the  skin  of  the  abdomen  substituted  for  that  of  the  fingers,  would  have 
constituted  organs  of  touch. — p. 

f  In  the  early  part  of  the  last  century,  an  anatomist  by  the  name  of  St. 
Andre,  exhibited  a  preparation  of  the  cuticle  which  appeared  to  be  injected 
with  mercury.  Ruysh  declared  the  thing  impossible,  and  invited  him  to  an 
investigation  of  the  subject.  This  invitation  was  not  accepted,  and  the  affair 
has  been  generally  considered  as  a  mistake  or  an  imposition. — H. 

*  Lectures  on  the  general  structure  of  the  human  body,  and  on  the  anatomy  and  functions 
of  the  skin,  by  J.  Chevalier. 

t  Lectures  on  the  structure  of  the  skin,  by  W.  Wallace,  London  Lancet,  1837. 


OF    THE    CUTICLE.  431 

It  extends  over  the  whole  external  surface  of  the  body, 
except  the  parts  covered  by  the  nails,  and  is  accommodated  to 
the  surface  of  the  skin,  by  forming  ridges  or  furrows,  cotfes- 
ponding  to  it. 

It  adheres  most  closely  to  the  cutis ;  and  when  abraded  by 
mechanical  violence,  the  surface  of  the  skin  appears  moistened 
by  effusion. 

It  is  not  certain  that  its  mode  of  union  with  the  skin  is 
perfectly  understood ;  the  adhesion  of  these  membranes  to 
each  other  is  as  uniform  as  that  of  two  smooth  surfaces  glued 
together,  but  it  is  generally  said  that  the  cuticle  is  attached  to 
the  cutis  by  very  numerous  and  fine  filaments. 

It  has  often  been  asserted  that  these  filaments  are  the 
exhaling  and  absorbing  vessels,  which  pass  through  the  cuticle, 
to  and  from  the  skin.  This  sentiment  appears  very  reasonable, 
but  no  vessels  that  pass  in  this  way  can  be  injected. 

There  are  innumerable  processes  which  pass  from  the  cuticle 
to  the  skin.  Many  of  these  are  the  linings  of  the  cavities  which 
contain  the  roots  of  the  hairs  ;  but  they  are  reported  by  micro- 
scopical observers  to  be  like  the  fingers  of  a  glove,  closed  at 
their  extremities. 

There  are  also  many  processes  which  contain  a  sebaceous 
substance  that  may  be  pressed  out  of  them  in  the  form  of 
worms  ;  these  are  the  ducts  of  sebaceous  glands. 

Besides  these,  there  is  an  immense  number  of  whitish  fila- 
ments, which  are  as  fine  as  the  most  delicate  thread  of  a  spider's 
web.  These  filaments  can  be  best  seen  while  the  cuticle  is 
separating  from  the  skin  of  the  sole  of  the  foot,  as  suggested  by 
Dr.  William  Hunter.*  They  are  supposed  to  be  vascular,  but 
they  have  never  been  injected. 

When  the  cuticle  is  in  its  natural  situation,  in  union  with  the 
skin,  there  appears  to  be  three  species  of  foramina  or  pores,  on 
its  external  surface:  viz.  1.  Those  formed  by  the  passage  of 
the  hairs ;  and  2.  Those  which  are  the  orifices  of  the  ducts  of 
the  sebaceous  glands  ;  each  of  which  has  been  already  men- 

*  See  the  London  Medical  Observations  and  Inquiries,  vol.  ii, — n. 


432  OF     THE    CUTICLE. 

tioned.     And  3.    Such  pores  as  exist  on  the  ends  of  the  fingers 
and  the  inside  of  the  hands. 

It  is  said  that  these  last  are  very  visible,  when  magnified  to 
twice  or  thrice  their  original  bulk,  and  drawings  of  them  have 
accordingly  been  made  by  Dr.  Grew*  and  by  Mr.  Cruikshank.f 
Small  specks  of  fluid  can  be  seen  with  the  naked  eye,  in  the 
same  situations,  in  warm  weather,  or  when  the  ends  of  the 
fingers  are  made  turgid  by  a  ligature.  It  is  probable  that  they 
are  formed  by  the  accumulation  of  fluid  at  these  orifices. 

The  above  described  pores  are  situated  on  the  ridges  at  the 
ends  of  the  fingers  and  not  in  the  furrows  ;  and  it  is  probable 
that  similar  pores  are  distributed  over  the  surface  of  the  body. 
,  Notwithstanding  the  appearance  of  these  foramina,  when 
the  cuticle  is  in  its  natural  situation,  several  of  the  most  suc- 
cessful investigators  of  the  subject  have  declared  that  they  could 
not  discover  any  pores  or  foramina  in  the  cuticle,  when  it  was 
separated  from  the  cutis. 

The  late  Professor  Meckel  of  Berlin,  who  was  one  of  this 
number,  was  induced  to  believe  that  the  matter  of  exhalation, 
and  of  absorption,  soaked  through  the  cuticle,  as  the  vapor  of 
warm  water  passes  through  leather.f 

In  support  of  this  doctrine  he  states  that  perspiration  goes  on 
through  the  cuticle  on  the  palms  of  the  hands  and  soles  of  the 
feet  when  it  is  very  thick  ;  and  observes,  that  if  it  were  trans- 
mitted by  delicate  vessels,  the  vessels  in  the  feet  must  be  torn 
by  the  weight  of  the  body,  in  persons  who  walk  ;  and  those  in 
the  hands  would  experience  the  same  fate,  in  laborers,  who  work 
with  heavy  hammers,  &tc. 

On  the  other  hand,  Mr.  Cruikshank,  who  could  likewise  find 
no  pores  in  the  separated  cuticle,  contends  strenuously  for  their 
existence  notwithstanding  ;  and  explains  their  non-appearance 
by  the  following  facts,  among  others ;  viz.  that  no  foramen  will 
appear  in  the  separated  cuticle,  although  it  has  been  punctured 
by  a  needle ;  and  that  when  the  cuticle  has  been  peeled  off, 

*  In  the  Philosophical  Transactions,  vol.  iii.  Lowthrop's  Abridgement. 

f  See  his  Experiments  on  Insensible  Perspiration. 

$  See  Memoirs  of  the  Royal  Academy  of  Sciences  of  Berlin,  vol.  xiii.  for  1757 . 


CAUSES  WHICH  PRODUCE  VESICATION.  433 

from  portions  of  the  cutis  on  which  were  hairs  which  must 
necessarily  have  perforated  it,  no  foramina  have  appeared 
in  it. 

M.  Bichat  took  very  different  ground :  he  asserted  that  the 
pores  of  the  separated  cuticle  were  to  be  seen  distinctly,  in 
large  numbers,  by  looking  through  it  towards  the  light ;  he  also 
believed  that  the  course  of  the  exhalent  vessels,  through  the 
cuticle,  might  be  seen  in  the  same  manner;  and  that  they 
passed  obliquely. 

That  the  cuticle  is  pervious,  is  proved  incontestably  by  the 
functions  of  perspiration  and  sweating,  as  well  as  of  absorption  ; 
but  there  are  good  reasons  for  believing  that  the  perforations 
of  the  cuticle  have  a  peculiar  structure  ;  and  are  not  simple 
foramina.  Thus,  when  a  vesicle  is  formed  by  the  operation  of 
cantharides  or  any  other  process,  if  the  cuticle  is  not  lacerated, 
it  will  confine  the  effused  fluid  for  a  considerable  time,  without 
any  appearance  of  its  escape  through  these  pores. 

This  fact,  which  is  strongly  opposed  to  the  hypothesis  of 
Meckel,  is  explained  by  Cruikshpnk  upon  the  supposition  that 
the  pores  of  the  skin  are  lined  by  processes  of  the  cuticle,  and 
that  when  the  cuticle  is  separated  from  the  cutis,  these  pro- 
cesses go  with  it,  and  act  like  valves  in  confining  the  fluid. 

Bichat  supposes  the  oblique  vessels  to  produce  the  same 
effect  upon  analogous  principles  ;  and  compares  their  situation 
to  that  of  the  ureters,  which  pass  obliquely  between  the  coats  of 
the  bladder. 

This  peculiar  quality  of  the  cuticle,  in  admitting  of  perspira- 
tion and  sweat,  and  also  absorption,  while  it  prevents  evapo- 
ration from  the  parts  which  it  encloses,  is  of  immense  impor- 
tance. 

If  a  portion  of  skin  be  deprived  of  cuticle  a  short  time  before 
death,  by  a  blister  for  example,  this  portion  will,  in  a  few  days, 
become  perfectly  dry  and  hard,  like  horn  ;  while  the  other  parts 
of  the  skin  of  the  subject,  covered  by  the  cuticle,  retain  their 
moisture  and  flexibility. 

It  may,  therefore,  be  admitted,  that  the  use  of  the  cuticle  is 
to  keep  the  -skin  soft  and  flexible,  by  confining  its  moisture,  as 
37 


434  SEPARATION  OF  THE  CUTICLE. 

well  as  to  defend  it.*  And  it  is  probable  tbat  the  sebaceous 
matter  is  secreted  for  the  purpose  of  preserving  the  cuticle  in  a 
state  of  flexibility. 

As  the  cuticle  is  capable  of  confining  fluid,  and  resisting  the 
action  of  chemical  agents,  it  is  surprising  that  epispastics  and 
rubefacients  should  act  through  it,  upon  the  skin,  with  so  much 
certainty  as  we  find  they  do»;  and  that  cantharides  should  pro- 
duce vesications,  when  applied  dry. 

The  thickness  of  the  cuticle  on  every  part  of  the  body  is 
much  increased  by  long  continued  pressure,  forming  corns  and 
excrescences  of  its  own  nature.  By  this  cause  also  it  is  ren- 
dered very  thick  on  the  palms  of  the  hands  and  soles  of  the 
feet ;  although  it  is  originally  thicker  there  than  in  other  parts. 

It  is  said  that,  after  long  boiling,  these  thick  portions  of  cuti- 
cle may  be  separated  into  distinct  lamina. 

In  the  living  subject,  the  cuticle,  when  immersed  in  warm 
water,  seems  to  absorb  some  of  that  fluid  ;  as  is  evinced  by  the 
hands  when  they  have  been  long  in  that  situation  ;  and  also  by 
those  parts  of  the  skin  to  which  poultices  have  been  applied. 

Notwithstanding  the  uniform  adhesion  of  the  cuticle  to  the 
cutis,  it  is  observed,  in  the  living  subject,  to  be  separated,  and 
formed  into  vesicles,  by  a  variety  of  causes,  viz. 

1.  Pinching  of  the  skin,  or  violent  mechanical  irritation  ;  such 
as  laboring  with  hard  instruments. 

2.  By  the  application  of  cantharides,  and  certain  other  sub- 
stances  which    produce    vesications.      Sometimes    these    sub- 
stances appear  to  inflame  the  skin  ;  but  on  other  occasions  the 
vesication    is    produced    while    the  skin   appears  unchanged  in 
color,  and  free  from  inflammation.      The  process  appears  dif- 
ferent from   that  of  simple  inflammation ;    for   certain   rubefa- 
cients often  inflame  the  skin  considerably  without  vesicating  or 
blistering  it. 

3.  Boiling  heat  will,  very  generally,  produce  vesication. 

4.  Certain  diseased  processes  seem  to  occasion  vesication  in 

*  This  property  of  the  cuticle  is  rendered  very  apparent  in  attempting  to  dry 
anatomical  preparations  with  the  skin  on,  in  which  the  student  will  fail,  unless 
the  cuticle  is  previously  removed  by  maceration. — p. 


CHEMICAL,  QUALITIES  OF  THE  CUTICLE.  435 

a  manner  which  is  not  well  understood,  viz.  erysipelas,  zona, 
or  shingles,  pemphigus,  and  some  other  eruptions  which  have 
no  name.  In  erysipelas  there  is  an  obvious  inflammation  of 
the  skin ;  but  in  some  of  the  other  diseases  the  vesication  takes 
place  without  the  appearance  of  inflammation. 

5.  Vesications   often   appear  when    there    is  a  tendency  to 
gangrene. 

6.  They  also  occur  in  some  cases  of  simple  fracture,  where 
there  is  considerable  injury.     In  these  cases  the  fluid  effused  is 
often  tinged  with  blood. 

After  death  the  cuticle  is  separated  from  the  cutis : 

1.  By  putrefaction;  in  which  case  large  vesicles  are  some- 
times formed. 

2.  By  long  continued  maceration, 

3.  By  boiling,  and 

4.  By  violent  dry  heat. 

The  cuticle  appears  to  be  least  deranged  when  it  is  separated 
by  putrefaction  and  maceration  :  in  these  cases  the  internal 
surface  corresponds  to  the  surface  of  the  skin  ;  and  the  pro- 
cesses which  contain  the  hairs,  as  well  as  those  which  are  the 
ducts  of  the  sebaceous  glands,  are  particularly  obvious. 

The  external  surface  of  the  cuticle  varies  in  different  places, 
according  to  the  surface  of  the  skin.  In  some  places  it  appears 
scaly  at  times,  and  has  therefore  been  supposed  to  consist 
entirely  of  scales  ;  but  in  other  parts,  when  examined  atten- 
tively, it  appears  like  a  half  transparent  concreted  substance, 
with  a  rough  surface. 

When  the  skin  has  continued  dry  for  a  long  time,  bran-like 
scales  can  be  rubbed  off  from  it.  These  are  probably  com- 
posed of  the  residuum  of  the  secretion  deposited  on  the  skin, 
and  of  a  portion  of  the  external  surface  of  the  cuticle.  The 
same  substance  appears  upon  the  first  washing  of  the  skin,  after 
that  process  has  been  discontinued  for  any  length  of  time. 

Many  speculations  have  arisen  respecting  the  manner  in  which 
the  cuticle  is  originally  formed,  and  reproduced  ;  but  none  of 
these  are  perfectly  satisfactory. 

It  is  also  a  question  whether  the  cuticle  is  endued  with  vitality, 


436  CHEMICAL  DUALITIES  OF  THE  CUTICLE. 

or  is  merely  an  inanimate  unorganized  concrete.  No  decisive 
argument  have  been  adduced  in  favor  of  its  vitality  ;  and  it 
has  already  been  stated,  that  neither  nerves  nor  vessels  can  be 
demonstrated  in  it. 

It  appears  particularly  calculated  for  protecting  the  skin 
which  it  covers  ;  for  it  is  insoluble  in  water,  and  resists  the 
action  of  several  powerful  Chemical  agents.  Thus,  it  is  not 
affected  by  immersion  for  a  considerable  time  m  the  sulphuric 
and  muriatic  acids  ;  although  the  nitric  acid  acts  upon  it. 

It  resists  for  a  short  time,  but  is  at  length  dissolved,  by  the 
pure  fixed  alkalies,  and  by  lime. 

It  is  supposed  by  the  chemists  to  consist  of  albumen,  in  a 
peculiar  state  of  modification. 

— Malpighi,  was  the  first  to  discover,  by  the  use  of  the 
microscope,  an  intervening  substance  between  the  cuticular 
covering,  and  the  cutis  vera,  which  he  called  the  rete  mucosum 
or  corpus  reticulare.  This  he  considered  the  seat  of  coloration 
in  the  negro,  and  asserted  the  cuticle  to  be  alike  in  all  varieties 
of  the  human  race — that  is,  colorless.  For  a  long  period  his 
researches  formed  the  basis  of  all  the  systematic  treatises  upon 
the  skin,  and  it  is  only  within  a  recent  period,  as  has  before 
been  observed,  that  the  study  of  the  subject  has  been  resumed. 
— The  cuticle  of  the  black  is  now  generally  admitted  to  be  of 
an  ashy  color.*  And  Flourensf  has  shown,  that  the  reticular 
appearance  of  the  rete  mucosum  is  entirely  an  adventitious 
circumstance.  Malpighi  first  discovered  his  rete  mucosum  on 

*  Breschet  has  asserted  that  the  color  of  the  skin  in  different  animals  is 
dependent  upon  the  form  of  the  scales  of  the  epidermis,  by  which  the  light  is 
reflected. 

Fig.  115.  The  larger  cut  represents,  after  this  observer,  the 

scales  of  the  epidermic  or  corneous  matter  of  a 
white  man,  diluted  with  water,  and  highly  magni- 
fied, in  which  are  seen  fragments  of  the  sudoriferous 
canals  and  inhalent  vessels.    The  scales  all  have  a 
trapezoidal  or  lozenge  shape.      The  smaller  cut, 
represents  a  single  scale  from  the  skin  of  a  whale, 
highly  magnified.    It  is  black  at  its  summit,  and 
whitish  at  its  pedicle  of  insertion.    The  skin  of  the  whale  is  black,  and  these 
writers  assert,  that  in  all  animals  with  black  skins,  including  negroes,  the  scales 
of  the  epidermis,  appear  under  the  microscope  of  this  shape  or  spatulate. — P. 
f  Annales  des  sciences  naturelles,  1837. — 


CHEMICAL  QUALITIES  OF  THE  CUTICLE.  437 

the  tongue  of  the  ox,  and  subsequently  under  the  epidermis  of 
the  human  hand,  from  which  he  drew  his  description.  By 
ebullition  he  softened  the  outer  covering  of  the  cutis  vera,>6nd 
then  tearing  off  the  epidermis,  he  saw  a  layer  of  soft  substance 
with  holes  in  it  like  the  meshes  of  a  net.  This  was  owing  to 
a  laceration  of  the  mucous  layer:  the  part  covering  the  apices 
of  the  villi  going  off  with  the  cuticle,  while  that  between  the 
villi  and  the  bases  of  the  papillae  adhered  to  the  cutis  vera. 
By  maceration  in  water,  which  is  the  surest  and  most  success- 
ful method  of  effecting  a  dissection  in  delicate  parts,  FJourens, 
found  in  the  same  organs  the  cuticle  to  come  off,  leaving  the 
whole  of  the  mucous  body  attached,  which  then  presented  none 
of  the  reticular  appearance.  The  cuticle  arid  mucous  body 
were  both  continuous  layers,  covering  the  papillae  and  forming 
their  sheaths.  The  sheaths  formed  by  the  latter  body  were 
broken  in  Malpighi's  preparation. 

— The  cuticular  sheaths  in  the  ox,  were  thin  and  delicate  over 
the  fungiform  or  smaller  papillae,  but  formed  thick  horny  layers 
over  the  larger  which  assist  in  the  action  of  mastication. 
— Albinus,  repeating  the  experiments  of  Malpighi,  corrected 
his  error,  and  in  the  beautiful  designs  of  Ladmiral,  has  repre- 
sented the  mucous  body  as  a  continuous  layer.  Since  then  by 
Bichat  and  others,  the  use  of  the  term  rete  mucosum,  has  been 
continued,  not  exactly  in  the  original  signification  of  Malpighi, 
but  under  the  belief  that  it  contained  a  net-work  of  vessels. 
Its  foliated  structure  has  been  well  established  by  Cruikshank, 
Gaultier,  and  Flourens.  It  thus  appears  that  the  whole  of 
the  anatomy  of  the  skin,  requires  to  be  constructed  anew. 
Several  of  the  German  and  French  anatomists  have  applied 
themselves  to  the  task,  among  whom  may  especially  be  men- 
tioned Weber*  of  Leipzig,  and  Breschet  of  Paris.f  The  views 
of  the  latter,  on  account  of  his  having  treated  the  subject  more 
extensively  than  the  rest,  as  well  as  from  his  high  situation  in 
the  school  of  Paris,  have  already  been  given.  The  physiology 

*  Arch,  fur  die  Physiologic. — 

f  Nouvelles  Recherches  sur  la  Structure  de  la  Peau,  par  G.  W.  Breschet  et 
Roussel  de  Vauzeme.    Paris,  1835.— 

37* 


438  CHEMICAL  DUALITIES  OF  THE  CUTICLE. 

of  cuticle  has  received  an  entirely  new  aspect,  from  recent 
observations,  and  especially  from  those  of  Henle.*  He  has 
shown  that  with  very  few  exceptions,  all  the  free  surfaces  of 
the  body — not  only  the  skin  which  has  its  cuticular  covering — 
but  those  of  the  serous  cavities,  the  mucous  passages,!  the 
blood-vessels,  and  the  ducts  of  the  glands,  are  invested  by  a 
membrane,  composed  of  one,  or  more  layers  of  primary  cells, 
forming  a  delicate  cuticle  or  epithelium.  The  epidermis, 
cuticle,  or  external  covering  of  the  skin,  when  examined  with 
a  powerful  microscope,  is  seen  to  be  composed  of  several  layers 
of  cells,  which  'are  the  consequence  of  an  uninterrupted  process 
of  exudation  which  has  place  upon  the  corion  or  true  skin. 
This  exudation,  though  unorganized,  retains  some  vital  proper- 
ties, and  is  a  cytablastema ;  that  is,  a  basis  structure,  or  soil/ 
from  which  new  growths  or  developments  take  place.  These 
new  growths  are  cytoblasts,  or  cell  germs ;  that  is,  cells  or 
vesicles,  at  first  globular,  afterwards  lenticular  and  opaque, 
(each  one  surrounding  a  central  nucleus),  which  possess  within 
themselves  the  inherent  principles  of  growth.^  The  more 
recently  produced  cells,  which  of  course  are  those  in  contact 
with  the  corion,  are  like  all  young  cells,  spherical  in  their 
figure ;  they  become  flattened  as  they  develop  themselves 
and  approach  the  surface ;  so  that  when  examined  on  a  sec- 
tion, they  are  found  to  have  undergone  changes  of  form  from 
that  of  a  globular  cell,  provided  with  a  nucleus,  to  that  of 
a  flat  scale,  in  which  no  trace  of  a  nucleus  appears,  and  which 
lay,  one  over  another,  like  so  many  layers  of  tiles  or  pavement. 
The  innermost  layers  are  soft  and  cellular;  the  outer  ones 
become  dried  on  the  surface  from  exposure  to  the  air,  and  fall 
off  in  squamae  or  scales. — § 


*  Allgera.  Anat.,  p.  260. 

f  Vide  Gen.  Anat.  of  Serous  and  Mucous  Membr.  Vol.  2. 

f  The  cell  germs,  here  and  in  other  parts  of  the  body,  bear  a  general  rela- 
tion to  the  size  of  the  blood  globules  of  the  same  individual.  This  is  a  remarka- 
ble fact,  and  somewhat  in  favor  of  the  views  of  Dr.  Barry,  who  states  that  it  is 
the  blood  disks  that  are  transformed  into  these  cell  germs. — Phil.  Trans.  Part 
11.  1840. 

§  Henle,  makes  three  varieties  of  epithelium  or  cuticle,  1st.  The  pavement- 
ed  sqnamous  or  tesselated  epithelium,  above  described,  found  on  the  skin,  serous 


THE    NAILS.  439 

The  Nails. 

The  roots  of  the  nails  appear  to  originate  in  a  fold  of  the 
cutis  vera,  from  the  epidermis  which  lines  the  fold  ;  but  "ihe 
bodies  of  the  nails  adhere  firmly  to  the  cutis  on  which  they  lie, 
and  appear  to  cover  it,  in  the  place  of  the  cuticle.  The  papillae 
of  those  parts  of  the  cutis  which  are  covered  by  the  nails  are 
very  conspicuous  when  the  nails  are  removed.  It  has  been 
supposed  that  there  was  no  rete  mucosum  between  the  nails  and 
cutis ;  but  this  opinion  is  probably  erroneous,  as  the  black  pig- 
ment is  perceptible  under  the  nails  of  some  negroes. 

The  nails  can  be  separated  from  the  cutis  by  all  those  pro- 
cesses which  separate  the  cuticle  from  it.  When  this  is  effected, 
they  remain  connected  with  the  cuticle,  which  appears  to  be 
continued  into  them  ;  and  on  this  account,  as  well  as  their 
insensibility,  and  their  resemblance  to  the  horny  excrescences  of 
the  cuticle,  they  are  considered  as  appendages  of  it. 

The  root  is  opaque,  and  appears  white.  The  body  is  trans- 
parent, and  in  health  shows  the  florid  color  of  the  cutis  which  it 
covers ;  but  the  color  of  this  portion  of  the  cutis  depends  upon 
the  state  of  the  circulation ;  and  becomes  livid  when  the  blood 
is  disoxygenated,  or  when  the  circulation  ceases  there ;  and  this 
color  also  appears  through  the  nails. 

The  nails  are  unquestionably  organized,  although  their  ultimate 
structure  is  not  known.  They  appear  to  be  composed  of  lamellae, 
and  these  lamellae  of  fibres.  They  grow  rapidly,  and  when 
they  are  not  pared  or  worn  away,  they  sometimes  acquire  an 
immense  size. 

As  a  remarkable  instance  of  this,  it  is  related,  that  a  nail  of 
the  great  toe  was  sent  from  Turin  to  the  Academy  of  Sciences 
at  Paris,  which  measured  four  inches  and  a  half  in  length. 

The  growth  seems  to  take  place  altogether  at  the  roots. 

The  nails,  when  chemically  examined,  appear  to  consist  of 


membranes,  the  lining  membrane  of  the  mouth,  pharynx,  oesophagus,  and  the 
vagina  and  cervix  uteri.  2d.  The  cylinder  epithelium,  found  in  the  remainder 
of  the  alimentary  canal,  the  ducts  of  the  glands,  and  a  great  part  of  the  genito- 
urinary apparatus  of  the  male.  3.  The  ciloary  epithelium,  found  in  the  respira- 
tory organs,  the  lachrymal  passages,  Eustachian  and  Fallopian  tubes,  etc. 
Vide  the  account  of  these  organs, 


440  THE    NAILS. 

a  modification  of  albumen  ;  and  thus  resemble  cuticle  and  horn 
in  their  composition. 

— The  growth   of  the  nails,  forwards,  is  entirely  from  a  fold 
of  the  cutis  vera,  at  its  root,  called,  though  not  with  exact  pro- 

priety,  the  matrix  of  the  nail,  as  seen 
iri  fig.  116.  It  grows  also  in  thickness 
%>m  the  upper  surface  of  the  skin, 
upon  which  the  nail  rests.  In  the 
formation  of  a  new  nail  the  la- 
men  which  starts  from  the  matrix, 
receives  successive  layers  from  be- 
neath, as  it  approaches  the  extremity,  the  deepest  seated  of 
which  is  the  shortest.  In  this  way  the  nail  gets  its  thickness  and 
strength,  and  occasionally,  where  the  deposition  of  new  matter, 
goes  on  more  rapidly  under  the  body  of  the  nail  than  at  the 
matrix,  the  body  is  thrown  up  into  unsightly  rugosities.  Its 
development  is  exactly  similar  to  that  of  the  horns  and  hoofs  of 
animals.  The  striated  appearances  of  the  nail,  is  said  to  be 
owing  to  the  papillary  prominences  below,  being  arranged  in  con- 
centric plicae.  The  white  semicircular  line  at  the  root,  is 
called  the  lunula. 

— The  nails  are  not  exactly  analogous  in  structure  to  the  cuticle, 
in  the  ordinary  acceptation  of  the  term — to  that  part  which  is 
raised  up  under  a  blister.  The  proper  cuticle  is  that  thin  coating 
which  is  scraped  away  and  worn  off  near  the  root,  and  which 
otherwise  would  cover  the  surface.  .  The  nails  consist  of  the 
proper  cuticle,  and  tunica  albuginea  superficialis  and  the  gem- 
mules  of  Gaultier — leaving  interposed  between  them  and  the 
cutis  vera,  the  tunica  albuginea  profunda  which  is  insensible,  and 
explains  why  it  is  that  a  splinter,  or  the  blade  of  a  small  pair 
of  scissors,  in  the  operation  for  onychia,  may  be  run  along 
close  on  the  under  surface  of  the  nail,  without  the  production 
of  much  pain.  According  to  Breschet,  the  nail  is  formed  like 
the  other  parts  of  the  horny  coat  exterior  to  the  cutis  vera,  by 
the  glands  for  the  secretion  of  the  mucous  and  coloring  matter ; 
the  products  of  which  would  be  mixed  up  together,  coloring  the 
substance  of  the  nail,  as  we  know  is  the  case  in  regard  to  the 
horns  and  hoofs  of  animals. — 


THE    HAIRS.  441 

The  Hairs 

Originate  from  bulbs  which  are  situated  at  the  bottom  of 
pores  or  cavities  in  the  skin.  These  pores  appear  to  be  Imed 
by  a  production  of  the  cuticle,  and  the  extremities  of  the  bulbs 
project  beyond  them  into  the  cellular  membrape.  In  some 
cases,  where  the  cuticle  is  separated  after  putrefaction,  it  seems 
that  these  lining  processes  of  the  cuticle  come  away  completely, 
and  bring  the  hairs  and  roots  with  them  ;  but  in  other  cases, 
the  cuticle  separates  from  the  cutis,  and  leaves  the  hairs  in  their 
natural  situation.* 

When  viewed  in  a  microscope,  the  bulb  appears  half  trans- 
parent, and  whitish  ;  and  of  a  softer  consistence  than  the  hair 
itself.  The  extremity  of  it  is  remarkably  flexible,  and  some- 
times much  darker  than  the  rest  of  the  bulb.  The  hair  does 
not  appear  to  extend  completely  to  the  end  of  the  bulb.  Neither 
blood-vessels  nor  nerves  have  been  traced  to  these  bulbs, 
although  it  is  probable  they  extend  there  ;  for  the  operation 
of  extracting  hair  by  the  roots  is  generally  very  painful ;  and 
blood  sometimes  appears  in  the  pore  from  which  the  hair  is 
extracted. 

The  body  of  the  hair  appears  to  be  composed  of  smaller 
fibres,  enclosed  in  a  membrane  which  often  is  imperfect  at  the 
extremity  ;  in  consequence  of  which  the  fibres  often  separate 
from  each  other,  or  split. 

Within  the  hair  is  diffused  the  substance  upon  which  its 
color  depends :  this  does  not  appear  to  be  essential  to  the 
structure,  as  in  the  advance  of  life  the  hair  is  so  generally 
without  it,  while  its  structure  continues  unchanged,  although  it 
becomes  less  flexible. 

The  color  of  the  hair  appears  to  have  some  connexion  with 


*  Dr.  Dom.  Nardo,  of  Padua,  asserts  that  he  has  succeeded  frequently  upon 
himself,  in  transplanting  a  hair  with  its  bulb,  from  one  of  the  pores  of  the  head 
into  one  of  the  pores  of  the  chest  ;  which  is  done  by  enlarging  the  latter  pore 
with  a  needle,  introducing  the  bulb  into  it  with  exactness,  and  exciting  a  slight 
inflammation  around  it  by  friction.  The  planted  hair  takes  root,  grows,  arid  in 
process  of  time,  undergoes  the  usual  changes, — becomes  gray,  and  is  shed. — 
Giorn  delV  ltd. — 


442  BULBS  OF  THE   HAIRS. 

the  color  of  the  rete  mucosum,  as  it  is  so  generally  black 
when  the  rete  mucosum  is  dark  colored. 

The  sudden  change  of  color  in  consequence  of  fright  or 
grief,  is  a  very  rare  occurrence  indeed ;  but  Bichat  relates 
an  instance  which  came  under  his  observation,  in  which  the 
hair  became  perfectly  white  in  one  night,  in  consequence  of 
grief. 

— The  substance  of  the  hair  is  of  a  corneous  nature  like  the 
epidermis.  Each  hair  consists  of  two  parts,  a  bulb  or  follicle, 
and  a  stalk  or  hair  proper. 

— The  follicle  is  ovoidal,  and  consists  of  two  membranes.  The 
exterior  is  white,  firm,  and  continuous  with  the  cutis  vera ;  the 
interior,  which  is  thin,  soft  and  reddish,  appears  to  be  continuous 
with  the  corneous  layers. 

— The  cavity  of  the  follicle  is  filled  up  at  the  bottom  with  a 
conical  papilla,  into  which,  according  to  Beclard,  the  nerves 
and  blood-vessels  may  be  seen  running  below.  Rudolphi  and 
Andral,  have  traced  nerves  into  the  whiskers  of  the  seal ; 
Shaw  has  done  the  same,  and  discovered  that  they  were 
branches  of  the  fifth  pair.  The  root  of  the  hair  possesses  a  coni- 
cal cavity,  in  which  is  lodged  the  point  of  the  papilla  which 
appears  to  secrete  the  matter  of  the  hair,  and  cause  its  growth, 
by  the  continuous  deposition  of  new  matter  at  its  root,  as  takes 
place  in  regard  to  the  nails  of  man,  and  the  horns  of  animals ; 
this  deposit  of  new  matter  in  the  fluid  state,  has  been  seen 
between  the  hair  and  papilla.  It  is  sometimes  secreted  in  pro- 
fusion, especially  in  the  head  ;  and  has  appeared  to  me,  by  over- 
flowing from  the  follicles,  and  drying  in  the  form  of  scales,  to 
be  the  source  of  the  dandriff. 

— The  epidermis  is  reflected  from  the  mouth  of  the  follicle,  and 
lost  upon  the  surface  of  the  hair. 

— The  hair,  when  examined  with  the  microscope,  appears  to 
be  covered  externally  with  small  scales,  and  to  be  hollow  inter- 
nally. The  latter,  however,  is  as  regards  the  human  hair,  an 
optical  illusion,  as  it  is  merely  loose  and  porous  or  pith-like  in 
its  central  part.  The  stalks  of  hairs  have  neither  vessels  nor 
nerves  in  their  structure,  and  anatomists  no  longer  admit 


STRUCTURE  OF  THE  HAIRS.  443 

a  fluid  in  their  interior  described   by  Bichat  and   others  as  the 
marrow.* 

— Around  the  orifices  of  the  follicle,  and  in  the  substance  o£/its 
neck  according  to  Gaultier,  we  find  a  number  of  minute 
sebaceous  glands,  that  secrete  an  unctuous  fluid,  which 
imbues  the  hair  and  preserves  its  softness  and  pliability.  The 
hairs  are  hygrometrical,  and  increase  in  length  and  thickness 
when  exposed  to  humidity  ;  and  are  shortened  again  by  dry  heat. 
— From  the  changes  which  take  place  in  regard  to  the  color 
of  the  hair,  there  is  reason  to  believe,  that  it  is  traversed  by 
some  fluid.  This  passes  along  the  hair  by  imbibition,  from 
the  root  upwards,  in  consequence  of  its  hygrometrical  nature, 
passing  up  through  the  spongy  or  cellular  tissue  of  which  the 
body  of  the  hair  appears  to  be  formed.  This  fluid  is 
derived  from  the  surface  of  the  skin  forming  the  papilla,  and 
is  analogous  to  the  fluid  of  the  rete  mucosum,  and  corresponds 
more  or  less  in  color  with  that  of  the  skin  and  iris. 
— The  hairs  vary  much  in  size,  but  appear  all  to  be  constructed 
on  the  same  plan.  They  have  different  names  in  different  parts 
of  the  body,  as  beard,  whiskers,  eyelashes,  &c.  The  minute 
hairs  generally  spread  over  the  body,  are  called  down  or 
duvette,  and  those  which  cover  the  scalp,  in  man,  have  particu- 
larly appropriated  to  them  the  term  of  hair.  In  the  white  or 
Caucasian  variety  of  the  human  race,  the  hairs  of  the  head  are 
very  numerous,  fine,  long,  and  vary  in  color  from  white  to 
black :  in  the  Mongolian  they  are  straight,  black  and  short : 
in  the  Negro,  black,  fine,  thick  and  crisped  :  in  the  Indian, 
black,  straight,  fine  and  thick:  and  in  the  Malay,  thick  and 
frizzled. 

— Their  size  and  number  vary  in  regard  to  their  color. 
Withoff,  has  calculated  that  in  a  quarter  of  an  inch  square  of 
skin  there  are  one  hundred  and  forty-seven  black  hairs,  one 
hundred  and  sixty-two  chestnut,  and  one  hundred  and  eighty- 
two,  blond. 
— The  hairs  are  composed  chemically,  agreeably  to  Vauquelin, 

4 

*  Note  to  Bichat,  4th  edit.  Paris. — 


444  CHEMICAL  COMPOSITION  OF  THE  HAIRS. 

chiefly  of  animal  matter,  of  some  concrete  white,  and  some 
black  oily  matter;  iron,  oxide  of  manganese,  phosphate  and 
carbonate  of  lime,  silex  and  sulphur.  The  change  of  color  to 
gray,  is  said  to  be  owing  to  a  preponderance  in  the  formation 
of  the  white  oily  substance,  and  the  development  of  some 
phosphate  of  magnesia.*  The  shape  of  the  hairs  vary  in  differ- 
ent parts. 

— From  the  large  size  of  the  nerves  which  enter  the  papilla?, 
to  which  the  hairs  are  attached,  they  become  in  many  animals 
delicate  instruments  of  touch.  The  formation  of  the  hair 
depends  upon  the  follicle  ;  while  this  remains  healthy,  though 
the  hair  should  be  removed  by  its  roots,  it  will  again  be  repro- 
duced. 

— Boucheron  in  a  recent  work  on  the  hair,  says  that  in  baldness 
the  bulbs  are  often  only  partially  atrophied,  a  circumstance 
which  does  not  render  hopeless  the  idea  of  their  recovering 
their  original  functions,  and  re-secreting  the  horny  matter 
which  forms  the  hair,  under  the  influence  of  certain  stimuli. 
— Round  the  bulbs  of  the  larger  hairs,  are  found  some  smaller 
ones,  which,  as  seen  in  extraction  of  the  former  in  some  cases 
of  tinea  capitis,  are  sometimes  developed  to  an  unusual  extent. 
— It  has  also  been  frequently  observed,  that  in  many  women 
the  almost  imperceptible  down  of  the  face  presents,  after  the 
fortieth  or  fiftieth  year  of  age,  a  great  increase  of  development. 
The  bulbs  of  the  hairs  are  obliquely  and  confusedly 
implanted  in  the  dermis — hence  when  one  straggling  white 
hair  is  extracted  from  the  head,  the  neighboring  ones  speedily 
whiten  in  their  turn  from  the  disturbance  and  injury  which  their 
bulbs  have  suffered. 

— There  are  many  hairs,  which  are  developed  so  feebly  that 
they  do  not  pass  the  epidermis,  but  roll  and  curve  themselves 
under  it.  From  accidental  circumstances  the  energy  of  the 
bulbs  of  these  hairs  is  sometimes  so  increased,  that  skin  which 
had  been  previously  smooth,  becomes  hairy.  Boucheron,  attri- 
butes the  color  of  the  hair  to  a  peculiar  animal  oil,  secreted 

*  C.  P.  Ollivier. 


CHEMICAL  COMPOSITION  OF  THE  HAIRS.  445 

by  the  bulbs,  and  varying  consequently  in  its  properties  in 
different  individuals.  It  is  to  a  change  in  the  color  of  this  oily 
matter,  arising  from  a  variety  of  causes,  which  enfeeble'  the 
general  system,  as  grief,  intense  study,  &c.,  that  is  attributed  the 
whitening  of  the  hair. — 

The  SKIN,  constructed  as  above  described,  answers  a  fourfold  purpose  in  the 
animal  economy.  It  is  the  organ  of  touch.  It  covers  and  protects  the  whole 
structure.  It  is  the  outlet  for  a  large  proportion  of  the  insensible  perspira- 
tion, and  it  performs  to  a  certain  extent  absorption. 

Many  facts  have  been  noticed  by  practitioners  of  medicine,  which  proves  that 
it  has  a  connexion  with  the  lungs  and  stomach,  which  is  not  yet  explained  by 
anatomy. 

As  one  of  these,  an  effect  of  the  urticaria  or  nettle-rash  may  be  mentioned. 
This  eruption  sometimes  relieves  completely  the  spasmodic  croup;  and  in 
other  cases,  nausea  and  vomiting. 

Some  children,  when  affected  with  this  species  of  croup,  are  relieved  by  rubbing 
the  skin  with  harsh  woolen  cloth. 

In  some  places,  the  urticaria  and  the  affection  of  respiration  are  so  much 
regarded  as  symptoms  of  the  same  disease,  that  the  term  hives  is  used  as  the 
name  for  each  of  them. 


38 


PART   V. 

OF  THE  NOSE,  THE  MOUTH,  AND  THE  THROAT. 
CHAPTER   XII. 

OF  THE  NOSE. 

THE  prominent  part  of  the  face,  to  which  the  word  nose  is 
exclusively  applied  in  ordinary  language,  is  the  anterior  covering 
of  two  cavities  which  contain  the  organ  of  smelling. 

These  cavities  are  formed  principally  by  the  upper  maxillary 
and  palate  bones ;  and,  therefore,  to  acquire  a  complete  idea  of 
them,  it  is  necessary  to  study  these  bones,  as  well  as  the  os 
ethmoides,  the  vomer,  and  the  ossa  spongiosa  inferiora,  which 
are  likewise  concerned  in  their  formation. 

In  addition  to  the  description  of  these  bones,  in  the  account 
of  the  bones  of  the  head,  it  will  be  useful  to  study  the  descrip- 
tion of  the  cavities  of  the  nose  which  follows  it,  (see  page  122.) 

After  thus  acquiring  a  knowledge  of  the  bony  structure,  the 
student  will  be  prepared  for  a  description  of  the  softer  parts. 

Of  the  External  Nose. 

The  superior  part  of  the  nose  is  formed  by  the  ossa  nasi,  and 
the  nasal  processes  of  the  upper  maxillary  bones,  which  have 
been  already  described,  (see  pages  86-89)  ;  but  the  inferior 
part,  which  is  composed  principally  of  cartilages,  is  much  more 
complex  in  its  structure. 

The  orifice,  formed  by  the  upper  maxillary  and  nasal  bones, 
is  divided  by  a  cartilaginous  plate,  which  is  the  anterior  and 
inferior  part  of  the  septum,  or  partition  between  the  two  cavi- 
ties of  the  nose.  The  anterior  edge  of  this  plate  projects  beyond 
the  orifice  in  the  bones,  and  continues  in  the  direction  of  the 


OF   THE  NOSE. 


447 


suture  between  the  ossa  nasi.  This  edge  forms  an  angle  with 
the  lower  edge  of  the  same  cartilage,  which  continues  from  it 
in  a  horizontal  direction,  until  it  reaches  the  lower  part  df  the 
orifice  of  the  nose,  at  the  junction  of  the  palatine  processes  of 
the  upper  maxillary  bones ;  where  a  bony  prominence  is 
formed,  to  which  it  is  firmly  united.  The  upper  part  of  the 
anterior  edge  of  this  cartilage,  which  is  in  contact  with  the  ossa 
nasi,  is  flat,  and,  is  continued  into  two  lateral  portions  that  are 
extended  from  it  one  on  each  side,  and  form  a  part  of  the  nose : 
these  lateral  portions  are  sometimes  spoken  of  as  distinct  carti- 
lages, (superior  lateral?)  but  they  are  really  continuations  of 
the  middle  portion  or  septum. 

Below  the  lower  edge  of  these  late- 
ral portions  are  situated  the  fibro  carti- 
lages which  form  the  orifices  of  the 
nose,  or  the  nostrils.  Of  these,  there  is 
one  of  considerable  size,  (inferior  late- 
ral,) and  several  small  fragments,  on 
each  side  of  the  septum.  Each  of  the 
larger  cartilages  forms  a  portion  of  an 
oval  ring,  which  is  placed  obliquely  on 
the  -side  of  the  septum  :  so  that  the 
extremity  of  the  oval  points  downward 
and  forward,  while  the  middle  part  of 
the  oval  is  directed  upwards  and  back- 
wards. The  sides  of  this  cartilage  are 
flat,  and  unequal  irf  breadth.  The  narrowest  side  is  internal, 
and  projects  lower  down  than  the  cartilaginous  septum  ;  so  that 
it  is  applied  to  its  fellow  of  the  other  nostril.  The  external 
side  is  broader,  and  continues  backward  and  upward  to  a  con- 
siderable distance. 

*  —a,  b,  Ossa  nasi,  which  show  above,  the  serrated  surface  by  which  they 
are  united  to  the  os  fronds,  c,  d,  Superior  lateral  cartilage,  e,  Vertical  carti- 
laginous septum  of  the  nose.  /,  /,  Sesamoid  cartilages,  filling  up  part  of  the 
vacuity  here.  gt  I,  Oval  or  inferior  lateral  cartilages,  or  cartilages  of  the  alse 
nasi ;  below  they  are  thin  and  curved  so  as  to  form  the  arch  of  the  anterior 
nares.  h,  i,  k,  Small  square  cartilages  appended  to  the  alae  nasi  and  circum- 
scribing the  outer  and  back  part  of  the  nostrils,  m,  n,  o,  Same  parts  of  the 
right  side. 


448  OF    THE  NOSE. 

The  upper  and  posterior  part  of  this  oval  ring  is  deficient ; 
but  the  remainder  of  the  nostril  consists  of  several  small  pieces 
of  cartilage,  (cartilages  carres,)  which  are  fixed  in  a  ligamen- 
tous  membrane  that  is  connected  by  each  of  its  extremities  to  the 
oval  cartilage,  and  thus  completes  the  orifice. 

The  anterior  parts  of  the  oval  cartilage  form  the  point  of  the 
nose ;  and  the  ligamentous  portions,  the  alae  or  lateral  parts  of 
the  nostrils. 

When  the  external  integuments  and  muscles  are  removed 
from  the  lower  portion  of  the  nose,  so  that  the  internal  mem- 
brane and  these  cartilages  only  remain,  the  internal  membrane 
will  be  found  attached  to  the  whole  bony  margin  of  each  orifice, 
and  to  each  side  of  the  whole  anterior  edge  of  the  middle 
cartilage,  which  projects  beyond  the  bones.  This  membrane  is 
afterwards  continued  so  as  to  line  the  oval  cartilages  and  the 
elastic  membrane  of  the  ala  nasi,  to  the  margin  of  the  orifice  of 
the  nostril. 

The  internal  portions  of  the  oval  cartilages  being  situated 
without  the  septum,  and  applied  to  each  other,  they  form  the 
external  edge  of  the  partition  between  the  nostrils,  or  the 
columna  nasi ;  which  is  very  movable  upon  the  edge  of  the 
middle  cartilage. 

The  orifices  of  the  nostrils,  thus  constructed,  are  dilated  by 
that  portion  of  the  muscle,  called  Levator  Labii  Superioris 
Alceque  Nasi,  which  is  inserted  into  the  alae  nasi. 

They  are  drawn  down  by  the  depressor  labii  superioris  alsque 
nasi.  They  are  pressed  against  the  septum  and  the  nose  by 
the  muscle  called  Compressor  Narisy  which  has  however  an 
opposite  effect  when  its  upper  extremity  is  drawn  upwards  by 
those  fibres  of  the  occipito  frontalis,  which  descend  upon  the 
nose,  and  are  in  contact  with  it. 

The  end  of  the  nose  is  also  occasionally  drawn  down,  by 
some  muscular  fibres  which  descend  from  it,  on  the  septum  of 
the  nose,  to  the  orbicularis  oris :  they  are  considered  as  a  por- 
tion of  this  muscle  by  many  anatomists,  but  were  described  by 
Albinus  as  a  separate  muscle,  and  called  Nasalis  Labii 


OF  THE  CAVITIES  OF    THE  NOSE.  449 

When  inspiration  takes  place  with  great  force,  the  alae  nasi 
would  be  pressed  against  the  septum,  if  they  were  not  drawn 
out  and  dilated  by  some  of  the  muscles  above  mentioned. 

Of  the  Cavities  of  the  Nose. 

To  the  description  of  the  osseous  parts  of  the  nasal  cavities 
in  page  89,  it  ought  now  to  be  added,  that  the  vacuity  in  the 
anterior  part  of  the  osseous  septum  is  filled  up  by  a  cartilaginous 
plate,  connected  with  the  nasal  lamella  of  the  ethmoid  bone 
above,  and  with  the  vomer  below.  This  plate  sends  off  those 
lateral  portions  already  described,  which  form  the  cartilaginous 
part  of  the  bridge  of  the  nose. 

It  should  also  be  observed  that  at  the  back  parts  of  these 
cavities  are  two  orifices  called  the  Posterior  Nares,  (see 
fig.  118,  p.  454,)  which  are  formed  by  the  palate  bones,  the 
vomer,  and  the  body  of  the  sphenoidal  bone,  and  are  somewhat 
oval. 

The  nasal  cavities,  thus  constructed,  are  lined  by  a  peculiar 
membrane,  which  is  called  pituitary  from  its  secretion  of  mucus, 
or  Schneiderian  after  the  anatomist  who  described  it  with  ac- 
curacy.* 

This  membrane  is  very  thick  and  strong,  and  abounds  with 
so  many  blood-vessels,  that  in  the  living  subject  it  is  of  a  red 
color.  It  adheres  to  the  bones  and  septum  of  the  nose  like 
the  periosteum,  but  separates  from  them  more  easily.  The 
surface  which  adheres  to  the  bones  has  some  resemblance  to 
periosteum,  while  the  other  surface  is  soft,  spongy,  and  rather 
villous.  Bichat  seems  to  have  considered  this  membrane  as 
formed  of  two  lamina,  viz.  periosteum,  and  the  proper  mucous 
membrane ;  but  he  adds,  that  it  is  almost  impossible  to  separate 
them. 

It  has  been  supposed  that  many  distinct  glandular  bodies 
were  to  be  seen  in  the  structure  of  this  membrane  by  examin- 
ing the  surface  next  to  the  bones  ;f  but  this  opinion  is  adopted 

*  Conrad  Schneider,  a  German  professor,  in  a  large  work,  "De  Catarrhis," 
published  about  1660. 
f  See  Winslow,  Section  X.  No.  337. 

38* 


450  SCHNEIDERIAN    MEMBRANE. 

by  very  few  of  the  anatomists  of  the  present  day.  The  texture 
of  the  membrane  appears  to  be  uniform;  and  on  its  surface  are 
a  great  number  of  follicles  of  various  sizes,  from  which  flows 
the  mucus  of  the  nose. 

These  follicles  appear  like  pits,  made  by  pushing  a  pin  ob- 
liquely into  a  surface  which  retains  the  form  of  the  impression. 
They  can  be  seen  very  distinctly  with  a  common  magnifying 
glass  when  the  membrane  is  immersed  in  water,  both  on  the 
septum  and  on  the  opposite  surface.  They  are  scattered  over 
the  membrane  without  order  or  regularity,  except  that  in  a  few 
places  they  occur  so  as  to  form  lines  of  various  lengths,  from 
half  an  inch  to  an  inch.  The  largest  of  them  are  in  the  lower 
parts  of  the  cavities. 

— The  surface  of  this  membrane  when  examined  with  the  mi- 
croscope, is  found  to  be  furnished  with  the  ciliary  epithelium, 
consisting  of  minute  projections  or  columns,  thickly  set  with 
fine  cilia  or  fringes,  which  have  a  peculiar  vibratile  motion  of 
their  own  for  carrying  on  fluids,  not  well  understood. — 

It  may  be  presumed  that  the  secretion  of  mucus  is  effected 
here  by  vessels  which  are  mere  continuations  of  arteries  spread 
upon  a  surface  analogous  to  the  exhalents,  and  not  convoluted 
in  circumscribed  masses,  as  in  the  case  of  ordinary  glands. 

The  arteries  of  this  membrane  are  derived  from  various 
sources  :  the  most  important  of  them  is  the  nasal  branch  of  the 
internal  maxillary,  which  passes  into  the  nose  through  the 
spheno-palatine  foramen,  and  is  therefore  called  the  Spheno- 
palatine  Artery.  It  divides  into  several  twigs,  which  are  spent 
upon  the  different  parts  of  the  surface  of  the  nasal  cavities. 
Two  of  them  are  generally  found  on  the  septum  of  the  nose  : 
one,  which  is  small,  passes  forwards  near  the  middle ;  the  other, 
which  is  much  larger,  is  near  the  lower  part  of  it. 

Two  small  arteries,  called  the  anterior  and  posterior  eth- 
moidals,  which  are  branches  of  the  ophthalmic,  enter  the  nose 
by  foramina  of  .the  cribriform  plate  of  the  ethmoidal  bone. 
These  arteries  pass  from  the  orbit  to  the  cavity  of  the  cranium, 
and  then  through  the  cribriform  plate  to  the  nose.  In  addition 
to  these,  there  are  some  small  arteries  derived  from  the  infra- 


OLFACTORY     NERVES.  451 

orbital,    the    alveolar   and    the    palatine,   which    extend  to  the 
Schneiderian  membrane;  but  they  are  not  of  much  importance. 

The  veins  of  the  nose  correspond  with  the  arteries.  Tliose 
which  accompany  the  ethmoidal  arteries  open  into  the  ocular 
vein  of  the  orbit,  which  terminates  in  the  cavernous  sinuses  of 
the  head.  The  other  veins  ultimately  terminate  in  the  external 
jugulars. 

The  nerves  of  the  nose  form  an  important  part  of  the  struc- 
ture ;  they  are  derived  from  several  sources ;  but  the  most 
important  branches  are  those  of  the  olfactory. 

The  olfactory  nerves  form  oblong  bulbs,  which  lie  on  each 
side  of  the  crista  gilli,  on  the  depressed  portions  of  the  cribri- 
form plate  of  the  ethmoid  bone,  within  the  dura  mater.  These 
bulbs  are  of  a  soft  consistence,  and  resemble  the  cortical  part  of 
the  brain  mixed  with  streaks  of  medullary  matter.  They  send 
off  numerous  filaments,  which  pass  through  the  foramina  of 
the  ethmoid  bone,  and  receive  a  coat  from  the  dura  mater  as 
they  pass  through  it. 

These  filaments  are  so  arranged  that  they  form  two  rows, 
one  running  near  to  the  septum,  and  the  other  to  the  surface  of 
the  cellular  part  of  the  ethmoid  bone,  and  the  os  turbinatum  : 
and  in  addition  to  these  are  some  intermediate  filaments. 

When  the  Schneiderian  membrane  is  peeled  from  the  bones  to 
which  it  is  attached,  these  nervous  filaments  are  seen  passing 
from  the  foramina  of  the  ethmoid  bone  to  the  attached  surfaces : 
one  row  passing  upon  that  which  covered  the  septum,  and  the 
other  to  that  of  the  opposite  side ;  while  the  intermediate  fila- 
ments take  an  anterior  direction,  but  unite  to  the  membrane  as 
soon  as  they  come  in  contact  with  it.\^~ 

All  of  these  can  be  traced  downwards  on  the  aforesaid  surfaces 
of  the  membrane  for  a  considerable  distance,  when  they  grad- 
ually sink  into  the  substance  of  the  membrane,  and  most  pro- 
bably terminate  on  the  internal  villous  surface ;  but  they  have 
not  been  traced  to  their  ultimate  termination.  They  ramify  so 
that  the  branches  form  very  acute  angles  with  each  other.  On 
the  septum  the  different  branches  are  arranged  so  as  to  form 


452     SPHENO-PALATINE  AND  OTHER  NERVES  OF  THE  NOSE. 

brushes,  which  lie  in  contact  with  each  other.     On  the  opposite 
sides,  the  different  ramifications  unite,  so  as  to  form  a  plexus. 

Dr.  Soemmering  has  published  some  very  elegant  engravings 
of  the  nose,  representing  one  of  his  dissections,  which  appears 
to  have  been  uncommonly  minute  and  successful.*  These 
represent  the  ramifications  as  becoming  more  expanded  and 
delicate  in  the  progress  towards  their  terminations,  and  as 
observing  a  tortuous  course,  with  very  short  meandering 
flexures. 

It  is  to  be  observed  that  the  ramifications  of  the  olfactory 
nerve,  thus  arranged,  do  not  extend  to  the  bottom  of  the  cavity. 
On  the  external  side,  they  are  not  traced  lower  than  the  lower 
edge  of  the  etbmoid,  or  of  the  superior  spongy  bone:  and  on 
the  septum,  they  do  not  extend  to  the  bottom,  although  they 
are  lower  than  the  opposite  side.  On  the  parts  of  the  mem- 
brane not  occupied  by  the  branches  of  the  olfactory  nerves, 
several  other  nerves  can  be  traced.  The  nasal  twig  of  the 
ophthalmic  branch  of  the  fifth  pair,  after  passing  from  the  orbit 
into  the  cavity  of  the  cranium,  proceeds  to  the  nasal  cavity  on 
each  side  by  a  foramen  of  the  cribriform  plate ;  and  after  send- 
ing off  some  fibrillae,  descends  upon  the  anterior  part  of  the 
septum  to  the  point  of  the  nose.  The  spheno-palatine  nerve, 
which  is  derived  from  the  second  branch  of  the  fifth  pair,  and 
enters  the  nose  by  the  spheno-palatine  foramen,  is  spread  upon 
the  lower  part  of  the  septum  and  of  the  opposite  side  of  the 
nose  also,  and  transmits  a  branch  through  a  canal  in  the  fora- 
men incisivum  to  the  mouth.  Several  small  branches  also  pass 
to  the  nose  from  the  palatine  and  other  nerves;  but  those 
already  mentioned  are  the  most  important. 

A  question  has  been  proposed,  whether  the  olfactory  nerve 
is  exclusively  concerned  in  the  function  of  smelling,  or  whether 
the  other  nerves  above  mentioned  are  also  concerned  in  it.  It 
seems  probable  that  this  function  is  exclusively  performed  by 
the  olfactory  nerve,  and  that  the  other  nerves  are  like  the 
ophthalmic  branch  of  the  fifth  pair,  with  respect  to  the  optic 

*  They  are  entitled,  Icones  Organorum  Humanorum  Olfactus. 


EXTENT  OF    THE   SCHNE1DER1AN    MEMBRANE.  453 

nerve.  In  proof  of  this,  it  is  asserted  that  the  sense  of  smelling 
has  entirely  ceased  in  some  cases,  where  the  sensibility  to 
mechanical  irritation  of  every  kind  has  remained  unchanged. 
If  the  olfactory  nerve  alone  is  concerned  in  the  function  of 
smelling  it  follows,  that  this  function  must  be  confined  to  the 

O'  ' 

upper  parts  of  the  nasal  cavities  ;  but  it  ought  to  be  remem- 
bered, that  the  structure  of  the  Schneiderian  membrane,  in  the 
lower  parts  of  these  cavities,  appears  exactly  like  that  which 
is  above. 

The  surface  of  the  nasal  cavities  and  their  septum,  when 
covered  with  the  Schneiderian  membrane,  correspond  with  the 
osseous  surface  formerly  described.  The  membrane  covers  the 
bones  and  cartilage  of  the  septum,  so  as  to  make  one  uniform 
regular  surface.  From  the  upper  part  of  the  septum,  it  is  con- 
tinued to  the  under  side  of  the  cribriform  plate  of  the  ethmoid, 
and  lines  it ;  the  filaments  of  the  olfactory  nerve  passing  through 
the  foramina  of  that  bone  into  the  fibrous  surface  of  the  mem- 
brane. It  is  continued  from  the  septum,  and  from  the  cribri- 
form plate,  to  the  internal  surface  of  the  external  nose,  and 
lines  it.  It  is  also  continued  backwards  to  the  anterior  surface 
of  the  body  of  the  sphenoidal  bone  ;  and,  passing  through  the 
foramina  or  openings  of  the  sphenoidal  cells,  it  lines  these 
cavities  completely  ;  but  in  these,  as  well  as  the  other  cavities, 
its  structure  appears  somewhat  changed  ;  it  becomes  thinner 
and  less  vascular. 

At  the  above  mentioned  foramina,  in  some  subjects,  it  forms 
a  plate  or  fold,  which  diminishes  the  aperture  considerably. 

From  the  upper  surface  of  the  nasal  cavities,  the  membrane 
is  continued  downwards  over  the  surface  opposite  to  the  sep- 
tum. On  the  upper  flat  surfaces  of  the  cellular  portions  of  the 
ethmoid,  it  forms  a  smooth  uniform  surface.  After  passing  over 
the  first  turbinated  bone,  or  that  called  after  Morgagni,  it  is 
reflected  into  the  groove,  or  upper  meatus  immediately  within 
and  under  it ;  the  fold  formed  by  the  membrane,  as  it  is  reflect- 
ed into  the  meatus,  is  rather  larger  than  the  bone  :  and  the 
edge  of  the  fold  therefore  extends  lower  down  than  the  edge 
of  the  bone,  and  partly  covers  the  meatus  like  a  flap,  consisting 


454 


EXTENT  OF    THE   SCHNEIDERIAN    MEMBRANE. 


only  of  the  double  membrane.  This  fold  generally  continues 
backwards  as  far  as  the  spheno-maxillary  foramen,  which  it 
closes  ;  the  periosteum,  exterior  to  the  foramen,  passing  through 
H,  and  blending  itself  with  the  fibrous  surface  of  the  Schneide- 
Fig.  118.* 


*  Fig.  118 — is  a  vertical  section,  exhibiting  a  profile  view  from  the  inside  of 
the  cavities  of  the  nostrils,  mouth,  and  pharynx,  a,  The  nose,  b,  Upper  lip, 
situated  in  front  of  the  palatine  arch,  which  runs  horizontally  backwards,  and 
divides  the  cavity  of  the  mouth  from  the  nasal  fossae,  c,  The  tongue,  the  base 
of  which  is  attached  to  the  os  hyoides  d.  e,  The  larynx,  suspended  from  the  os 
hyoides,  by  the  thyreo-hoid  ligaments  which  are  seen  intervening ;  it  opens 
backwards  towards  the  pharynx.  /,  Trachea,  g,  Cuneiform  process  of  the 
occipital  bone,  united  to  the  body  of  the  sphenoid,  and  to  which  is  chiefly 
suspended  the  pharynx  h,  which  is  laid  open  (in  order  to  show  its  shape  and 
position)  by  the  removal  of  its  right  half,  and  is  seen  terminating  below  opposite 
the  cricoid  cartilage  in  the  ossophagus.  i,  Commencement  of  the  resophagus. 
7;,  Section  of  the  velum  pendulum  palatae,  the  lower  point  of  which  constitutes 
the  uvula;  above  this  is  seen  the  opening  of  the  posterior  nares,  7,  into  the 
top  part  of  the  cavity  of  the  pharynx  ;  below  this  are  seen  the  two  half  arches 
of  the  palate,  o,  Posterior  half  arch,  r,  Anterior  half  arch,  the  space  or 
cavity  between  these  occupied  by  the  tonsil  gland  or  amygdala  p.  7,  Sublingual 


DISTRIBUTION  OF  THE   SCHNEIDERIAN  MEMBRANE.  455 

nan  membrane  within.  Here  the  spheno-palatine  nerves  and 
arteries  join  the  membrane.  Below  this  meatus,  it  extends 
over  the  middle,  (formerly  called  the  upper,)  turbinated  bope, 
and  is  reflected  or  folded  inwards  on  the  under  side  of  this  bone, 
and  continued  into  the  middle  meatus  below  it.  In  the  middle 
meatus,  which  is  partly  covered  by  the  last  mentioned  turbina- 
ted bone,  there  are  two  foramina  ;  one  communicating  with  the 
maxillary  sinus,  and  the  other  with  the  anterior  cells  of  the 
ethmoid  and  the  frontal  sinuses.  The  aperture  into  the  maxil- 
lary sinuses  is  much  less  in  the  recent  head,  in  which  the 
Schneiderian  membrane  lines  the  nose,  than  it  is  in  the  bare 
bones.  A  portion  of  the  aperture  in  the  bones  is  closed  by  the 
Schneiderian  membrane,  which  is  extended  over  it :  the  re- 
mainder of  the  aperture  is  unclosed  ;  and  through  this  foramen, 
the  membrane  is  reflected  so  as  to  line  the  whole  cavity.  As  a 
portion  of  the  foramen  is  covered  by  the 'membrane,  and  this 
portion,  as  well  as  the  other  parts  of  the  cavity,  is  lined  by  the 
membrane,  it  is  obvious  that  at  the  place  where  the  membrane 
is  extended  over  the  foramen  in  the  bone,  it  must  be  doubled ; 
or,  in  other  words,  a  part  of  the  aperture  of  the  maxillary  sinus 
is  closed  by  a  fold  of  the  Schneiderian  membrane.* 

This  aperture  varies  in  size  in  different  subjects,  and  is  often 
equal  in  diameter  to  a  common   quill.     It   is  situated  in   the 


gland,  placed  under  the  tongue,  and  communicating  with  the  mouth  by  a  small 
duct,  (ductus  Bartholinus :)  many  small  ducts  from  this  gland,  open  into  the 
duct  of  the  gland  below,  m,  Sub- maxillary  gland,  situated  below  and  behind 
the  preceding  gland,  n,  Thyroid  gland,  s,  Vertical  section  of  the  border  of 
the  cervical  vertebrae,  to  which  the  pharynx  is  attached  by  cellular  tissue. 
tj  Spinal  canal,  u,  Section  of  spinous  processes  and  muscles  of  the  neck. 
v,  Left  nostril.  TV,  Bony  palate,  z,  Trumpet-shaped  orifice  of  the  Eustachian 
tube,  y,  Inferior  turbinated  bone,  covered  by  the  Schneiderian  membrane. 
z,  Middle  turbinated  bone.  1,  Superior  turbinated  bone,  both  covered  with  the 
same  membrane.  2,  Superior  meatus.  3,  Middle  meatus.  4,  Inferior  meatus. 
5,  Place  of  opening  of  the  ductus  ad  nasum.  6,  Frontal  sinuses.  7,  The 
posterior  nares.  8,  Sphenoidal  cell  in  the  body  of  the  sphenoid  bone,  showing 
the  orifice  below,  by  which  it  communicates  with  the  top  of  the  pharynx  ;  above 
is  seen  the  sella  turcica  of  the  sphenoid  bone. 

*  In  the  mucous  membrane  lining  the  cavities  of  the  maxillary,  sphenoid 
and  ethmoid  bones,  no  one  has  yet  detected  any  mucous  follicles.  The  pouch 
formed  by  the  reflection  of  the  membrane,  seems  itself  to  constitute  a  large 
follicle,  from  which  mucus  is  abundantly  secreted. — r. 


456         OBSERVATIONS  RESPECTING  THE  NOSE. 

middle  of  the  meatus,  and  is  covered  by  the  middle  turbinatedv 
bone  immediately  above  it, — a  prominence  of  the  cellular 
structure  of  the  ethmoid  bone,  which  has  a  curved  or  semicir- 
cular figure.  Near  this  prominence,  in  the  same  meatus,  a 
groove  terminates,  which  leads  from  the  anterior  ethmoid  cells 
and  the  frontal  sinuses. 

From  the  middle  meati^s,  the  membrane  proceeds  over,  the 
inferior  turbinated  bone,  and  is  reflected  round  and  under  it 
into  the  lower  meatus.  It  appears  rather  larger  than  the  bone 
which  it  covers ;  and  therefore  the  lower  edge  of  the  bone  does 
not  extend  so  low  as  the  lower  edge  of  the  membrane,  which 
of  course  is  like  a  fold  or  plait.  The  membrane  then  continues 
and  lines  the  lower  meatus :  here  it  appears  less  full  than  it  is 
in  the  turbinated  bone.  In  this  meatus,  near  to  its  anterior 
end,  is  the  lower  orifice  of  the  lachrymal  duct ;  this  is  simply 
lined  by  the  Schneiderian  membrane,  which  is  continued  into 
it,  and  forms  no  plaits  or  folds  that  effect  the  orifice. 

Orifice  of  the  Eustachian  Tube. 

Immediately  behind  each  of  the  nasal  cavities,  on  the  exter- 
nal side,  is  the  orifice  of  the  Eustachian  Tube.  It  has  an  oval 
form,  and  is  large  enough  to  admit  a  very  large  quill.  Its  posi- 
tion is  oblique:  the  upper  extremity  being  anterior  to  the  other 
parts  of  the  aperture,  and  on  a^  line  with  the  middle  meatus, 
while  the  centre  is  benind  the  inferior  turbinated  bone.  The 
lower  part  of  the  oval  is  deficient.  This  tube  is  formed  poste- 
riorly by  a  cartilaginous  plate.  It  is  lined  by  the  membrane 
continued  from  the  nose. 

The  cavities  of  the  nose  answer  a  twofold  purpose  in  the  animal  economy ; 
they  afford  a  surface  for  the  expansion  of  the  olfactory  nerves,  and  a  passage 
for  the  external  air  to  the  windpipe,  in  respiration. 

The  function  of  smelling  appears  to  be  dependent,  to  a  certain  degree,  upon 
respiration.  It  has  been  asserted  that  unless  the  air  passes  in  a  stream 
through  the  nose,  as  in  respiration,  the  perception  of  odor  does  not  take 
place ;  that  in  persons  who  breathe  through  wounds  and  apertures  in  the 
windpipe,  the  function  of  smelling  is  not  performed.  It  is  rather  in  confir- 
mation of  this  proposition,  that  most  persons,  when  they  wish  to  have  an 
accurate  perception  of  any  odor,  draw  in  air  rapidly  through  the  nose. 

Although  the  ultimate  termination  of  the  olfactory  nerves  cannot  be  demon- 
strated like  those  of  the  optic  and  auditory  nerves,  it  is  probable,  from  the 


USES  OF    THE  SINUSES  OF  THE  NOSE.  457 

appearance  of  the  fibres,  while  they  are  distinguishable,  that  they  are  finally 
arranged  with  great  delicacy.  It  is  certain  that  the  impressions  from  whence 
we  derive  the  perceptions  of  many  odors,  must  be  very  slight,  as  some 
odorous  bodies  will  impregnate  the  air  of  a  large  chamber  for  a  great  length 
of  time,  without  losing  any  sensible  weight. 

With  respect  to  delicacy  of  structure  and  sensibility,  it  is  probable  that  the  nose 
holds  a  middle  rank  between  the  eye  or  ear,  and  the  tongue :  and  on  this 
account  the  mucus  is  necessary  as  a  covering  and  defence  of  its  surface. 

It  has  been  ascertained,  by  the  investigations  of  chemists,  that  this  mucus  con- 
tains the  same  ingredients  as  the  tears  already  described,  namely,  animal 
mucus  and  water ;  and  muriate  of  soda,  and  soda  uncombined  j  phosphate  of 
lime,  and  phosphate  of  soda. 

The  animal  mucus,  which  is  a  most  important  ingredient  in  the  composition, 
resembles  the  mucilage  formed  by  some  of  the  vegetable  gums  in  several 
particulars  ;  and  differs  from  them  in  others. 

The  mucus  of  the  nose,  if  it  remain  there  long  after  it  is  secreted,  becomes 
much  more  viscid  in  consistence,  and  changes  from  a  whitish  color  to  one 
which  partakes  more  or  less  of  the  yellow.  It  is  probable  that  an  incipient 
putrefaction  may  occasion  these  changes  in  it. 

The  use  of  the  frontal,  maxillary  and  other  sinuses,  communicating  with  the 
nose,  has  been  the  subject  of  some  inquiry.  As  there  can  be  no  stream  of 
air  through  them,  and  as  the  membrane  lining  them  is  neither  so  thick,  villous 
nor  flexible  as  that  lining  the  nose,  it  may  be  concluded,  a  priori,  that  they 
are  not  concerned  in  the  function  of  smelling.  This  opinion  is  strengthened 
by  the  fact,  that  very  young  children,  in  whom  these  sinuses  scarcely  exist, 
enjoy  the  sense  of  smelling  in  perfection.  The  following  fact  is  also  in  sup- 
port of  it.  The  celebrated  Desault  attended  a  patient,  in  whom  one  of  the 
frontal  sinuses  was  laid  open  by  the  destruction  of  the  bone  which  covered  it 
anteriorly.  This  patient  was  able  to  breathe  a  short  time  through  the  sinus 
when  the  mouth  and  nose  were  closed :  at  the  request  of  Desault  he  breathed 
in  this  manner  when  a  cup  of  some  aromatic  liquor  was  held  near  the  open- 
ing of  the  sinus,  and  had  not  the  least  perception  of  odor.  This  experiment 
was  repeated  several  times. 

Many  physiologists  believe  that  these  sinuses  have  an  effect  in  modulating  the 


39 


458  OF   THE  MOUTH. 


CHAPTER  XIII. 

OF   THE    MOUTH. 

THE  general  cavity  of  the  mouth  is  formed  anteriorly  and 
laterally  by  the  connexion  of  the  lips  and  cheeks  to  the  upper 
and  lower  jaws ;  so  that  the  teeth  and  the  alveoli  of  both  jaws 
may  be  considered  as  within  the  cavity.  Above,  it  is  bounded 
principally  by  the  palatine  processes  of  the  upper  maxillary 
and  palate  bones,  and  the  soft  palate,  which  continues  back- 
ward from  them  in  the  same  direction. 

Below,  the  cavity  is  completed  by  several  muscles,  which 
proceed  from  almost  the  whole  internal  circumference  of  the 
lower  jaw,  and,  by  their  connexions  with  each  other,  with  the 
tongue  and  the  os  hyoides,  form  a  floor  or  bottom  to  it.  The 
tongue  is  particularly  connected  to  this  surface,  and  may  be 
considered  as  resting  upon  and  supported  by  it. 

To  acquire  an  idea  of  the  parietes  of  this  cavity,  after 
studying  the  upper  and  lower  maxillary  bones,  the  orbicularis 
oris  and  the  muscles  connected  with  it,  especially  the  buccina- 
tor, ought  to  be  examined ;  and  also  the  diagastricus,  the 
mylo-hyoideus,  genio-hyoideus,  and  genio-hyoglossus.  By 
this  it  will  appear  that  the  lips  and  cheeks,  and  the  basis  or 
floor  of  the  mouth,  are  formed  in  a  great  measure  by  muscles. 
Upon  the  internal  surface  of  these  muscles,  a  portion  of  cellular 
and  adipose  substance  is  arranged,  as  well  as  glandular  bodies 
of  different  sizes  ;  and  to  these  is  attached  the  membrane  which 
lines  the  inside  of  the  mouth. 

This  membrane  passes  from  the  skin  of  the  face  to  the  lips, 
and  the  inside  of  the  mouth ;  and,  although  it  is  really  a  con- 
tinuation of  the  skin,  there  is  so  great  a  change  of  structure  that 
it  ought  to  be  considered  as  a  different  membrane.  At  the 
orifice  of  the  lips  it  is  extremely  thin,  and  so  vascular,  that  it 


INTERNAL  SURFACE  OF  THE  MOUTH. GUMS.       459 

produces  the  fine  florid  color  which  appears  there  in  health. 
It  is  covered  by  a  cuticle,  called  by  some  anatomists,  Epithe- 
lium, which  has  a  proportionate  degree  of  delicacy,  and  carf  be 
separated  like  the  cuticle  in  other  parts.  When  this  cuticle  is 
separated,  the  lips  and  the  membrane  of  the  mouth  appear  to 
be  covered  with  very  fine  villi,  which  are  particularly  apparent 
in  some  preparations  of  the  lips  after  injection  and  maceration.* 

Under  this  membrane  are  many  small  glandular  bodies  of  a 
roundish  form,  called  glandulae  labiales,  whose  excretory  ducts 
pass  through  it  to  the  inner  surface  of  the  mouth,  for  the  pur- 
pose of  lubrifying  it  with  their  secretion,  which  is  mingled  with 
the  saliva. 

The  membrane  which  lines  the  inside  of  the  lips  and  cheeks, 
is  somewhat  different  from  that  which  forms  the  surface  of  the 
orifice  of  the  mouth  :  it  is  not  so  florid  ;  the  blood-vessels  in 
its  texture  are  larger,  and  not  so  numerous.  This  change, 
however,  takes  place  very  gradually,  in  the  progress  of  the 
membrane,  from  the  orifice  of  the  lips  to  the  back  part  of  the 
cheeks.  Glandular  bodies,  like  those  of  the  lips,  are  situated 
immediately  exterior  to  this  membrane  of  the  cheeks,  between 
it  and  the  muscles :  their  ducts  open  on  its  surface.  These 
glands  are  called  Buccales. 

This  lining  membrane  is  continued  from  the  internal  surface 
of  the  lips  and  cheeks  to  the  alveolar  portions  of  the  upper  and 
lower  jaws,  which  are  in  the  cavity  of  the  mouth,  and  covers 
them,  adhering  firmly  to  the  periosteum. 

The  teeth  appear  to  have  passed  through  apertures  in  this 
membrane,  and  are  surrounded  by  it  closely  at  their  respective 
necks. 

The  portion  of  membrane,  which  thus  invests  the  jaws,  con- 
stitutes the  gums  ;  which  have  now  acquired  a  texture  very 
different  from  that  of  the  membrane  from  which  they  were 
continued.  They  are  extremely  firm  and  dense,  and  very 
vascular.  It  is  probable  that  their  ultimate  structure  is  not 
perfectly  understood. 

*  Ruysch  had  a  fine  preparation  of  this  structure.  See  Thesaurus  VII.  Tab. 
III.  Fig.  5. 


460  MEMBRANE  LINING  THE  HARD  OR  BONY   PALATE. 

In  the  disease  called  scurvy,  they  tumefy  and  lose  the  firm- 
ness of  their  texture  :  they  acquire  a  livid  color,  and  are  much 
disposed  to  hemorrhage. 

From  the  alveoli  of  the  upper  jaw,  the  lining  membrane  is 
continued  upon  the  palatine  processes  of  the  upper  maxillary 
and  palate  bones,  or  the  roof  of  the  mouth. 

The  membrane  of  the  palate  is  not  quite  so  firm  as"  that  of 
the  gums,  and  is  also  less  florid  :  it  adheres  firmly  to  the  peri- 
osteum, and  thus  is  closely  fixed  to  the  bones.  There  is  gene- 
rally a  ridge  on  its  surface,  immediately  under  the  suture  be- 
tween the  two  upper  maxillary  bones  ;  and  some  transverse 
ridges  are  also  to  be  seen  upon  it.  On  the  internal  surface  of 
this  membrane,  are  small  glandular  bodies,  whose  ducts  open  on 
the  surface  of  the  palate. 

It  is  asserted,  that  this  membrane  has  a  limited  degree  of  that 
sensibility  which  is  essential  to  the  functions  of  tasting  ;  and 
that  if  certain  sapid  substances  are  carefully  applied  to  it,  their 
respective  tastes  will  be  perceived,  although  they  have  not  been 
in  contact  with  the  tongue. 

The  membrane  is  continued  from  the  bones  above  mentioned 
to  the  soft  palate,  or  velum  pendulum  palati,  which  is  situated 
immediately  behind  them.  This  soft  palate  may  be  considered 
as  a  continuation  of  the  partition  between  the  nose  and  mouth ; 
it  is  attached  to  the  posterior  edge  of  the  palatine  processes  of 
the  ossa  palati,  and  to  the  pterygoid  processes  of  the  sphenoidal 
bone.  Its  interior  structure  is  muscular.  The  upper  surface  is 
covered  by  the  membrane  of  the  nose,  the  lower  surface  by  the 
membrane  which  lines  the  mouth. 

The  muscles,  which  contribute  to  the  composition  of  this 
structure,  are  the  circumflexi  and  the  levatores  palatii  above, 
and  the  constrictores  isthmi  faucium  and  palato-pharyngei  below. 
(See  pages  318,  319.)  Thus  composed,  the  soft  palate  con- 
stitutes the  back  part  of  the  partition  between  the  nose  and 
mouth.  When  viewed  from  before,  with  the  mouth  open,  it 
presents  towards  the  tongue  an  arched  surface,  which  continues 
downwards  on  each  side,  until  it  comes  nearly  in  contact  with 
the  edges  of  that  organ.  On  each  of  the  lateral  parts  of  this 


SOFT    PALATE. UVULA.  461 

arch,  are  two  pillars,  or  rather  prominent  ridges,  which  project 
into  the  mouth.  These  ridges  are  at  some  distance  from  each 
other  below,  and  approach  much  nearer  above,  so  that  *hey 
include  a  triangular  space.  They  are  called  the  lateral  half 
arches  of  the  palate,  (see  fig.  118,  p.  455.)  Each  of  them  is 
formed  by  a  plate  or  fold  of  the  lining  membrane  of  the  mouth, 
and  contains  one  of  the  two  last  mentioned  muscles  ;  the  anterior, 
the  constrictor  isthmii  faucium ;  the  posterior,  the  palato- 
pharyngeus.  These  muscles,  of  course,  draw  the  palate  down 
toward  the  tongue  when  they  contract. 

From  the  centre  of  the  arch,  near  its  posterior  edge,  is  sus- 
pended the  uvula,  a  conical  body,  which  varies  in  length  from 
less  than  half  an  inch,  to  rather  more  than  one  inch.  It  is 
connected  by  its  basis  to  the  palate;  but  its  apex  is  loose  and 
pendulous.  This  body  is  covered  by  the  lining  membrane  of 
the  mouth.  It  contains  many  small  glands,  and  a  muscle  also, 
the  azygos  uvulae,  which  arises  from  the  posterior  edge  of  the 
ossa  palati,  at  the  suture  which  connects  them  to  each  other, 
and,  passing  posteriorly  upon  the  soft  palate,  extends  from  the 
basis  to  the  apex  of  the  uvula,  into  which  it  is  inserted.  By 
the  action  of  this  muscle,  the  length  of  the  uvula  can  be  very 
much  diminished  :  and  when  its  contraction  ceases,  that  body  is 
elongated.* 

The  pendulous  part  of  the  uvula  can  also  be  moved,  in  certain 
cases,  to  either  side. 

It  is  commonly  supposed,  that  the  principal  use  of  this  little 
organ  is  to  modulate  the  voice ;  but  there  are  good  reasons  for 
believing,  that  it  has  another  object.  It  was  remarked  by 
Fallopius,  (and  the  observation  has  been  confirmed  by  many 
surgeons  since  his  time,)  that  the  uvula  may  be  removed  com- 
pletely without  occasioning  any  alteration  of  the  voice,  or  any 
difficulty  of  deglutition,  if  the  soft  palate  be  left  entire. 

The  soft  palate  is  so  flexible,  that  it  yields  to  the  actions  of 
the  levatores  palati,  which  draw  it  up  so  as  to  close  the  posterior 
nares  completely. 

*  A  careful  dissection,  shows  two  of  these  muscles. — p. 
39* 


462  THE  TONGUE. 

It  also  yields  to  the  circumflexi  or  tensores,  which  stretch  it  so 
as  to  do  away  its  arched  appearance. 

It  is  therefore  very  properly  called  the  Palatum  Molle,  or 
soft  palate.  It  is  also  frequently  called  the  Velum  Pendulum 
Palati,  from  the  position  which  it  assumes. 

The  Tongue, 

which  is  a  very  important  part  of  this  structure,  is  retained  in 
its  position  and  connected  with  the  parts  adjoining  it,  by  the 
following  arrangements. 

The  os  hyoides,  which,  as  its  name  imports,  resembles  the 
Greek  letter  v,  or  half  an  oval,  is  situated  rather  below  the 
angles  of  the  lower  jaw,  in  the  middle  of  the  upper  part  of  the 
neck.  It  is  retained  in  its  position  by  the  sterno-hyoidei 
muscles,  which  connect  it  to  the  upper  part  of  the  sternum,  by 
the  coraco,  or  omo-hyoidei,  which  pass  to  it  obliquely  from  the 
scapula ;  by  the  thyro-hyoidei,  which  pass  to  it  directly 
upward  from  the  thyroid  cartilage,  all  of  which  connect  it  to 
parts  below.  To  these  should  be  added  the  stylo-hyoidei,  which 
pass  to  it  obliquely  from  behind  and  rather  from  above :  the 
mylo-hyoidei,  which  come  rather  anteriorly  from  the  lateral 
parts  of  the  lower  jaw;  and  the  genio-hyoidei,  which  arises 
from  a  situation  directly  anterior  and  superior  to  the  chin. 
When  these  muscles  are  at  rest,  the  situation  of  the  os  hyoides 
is,  as  above  described,  below  the  angles  of  the  lower  jaw : 
when  those,  in  one  particular  direction  act,  while  the  others 
are  passive,  the  bone  may  be  moved  upwards  or  downwards, 
backwards  or  forwards,  or  to  either  side.  This  bone  may  be 
considered  as  the  basis  of  the  tongue ;  for  the  posterior  extrem- 
ity of  that  organ  is  attached  to  it,  and  of  course  the  move- 
ments of  the  bone  must  have  an  immediate  effect  upon  those  of 
the  tongue. 

The  tongue  is  a  flat  body  of  an  oval  figure,  but  subject  to 
considerable  changes  of  form. 

The  posterior  extremity,  connected  to  the  os  hyoides,  is  com- 
monly called  its  base ;  the  anterior  extremity,  which,  when  the 
tongue  is  quiescent,  is  rather  more  acute,  is  called  its  apex. 

The  lower  surface  of  the  tongue  is  connected  with  a  number 


STRUCTURE  OF  THE  TONGUE.  463 

of  muscles,  which  are  continued  into  its  substance.  This  con- 
nexion is  such,  that  the  edges  of  the  tongue  are  perfectly  free 
and  unconnected  ;  and  so  is  the  anterior  extremity  for  a  con- 
siderable distance  from  the  apex  towards  the  base. 

The  substance  of  the  tongue  consists  principally-  of  muscu- 
lar fibres  intermixed  with  a  delicate  adipose  substance.  It  is 
connected  to  the  os  hyoides  by  the  hyo-glossus  muscle,  and  also 
by  some  other  muscular  fibres,  as  well  as  by  a  dense  mem- 
branous substance,  which  appears  to  perform  the  part  of  a 
ligament.  This  connexion  is  also  strengthened  by  the  con- 
tinuance of  the  integuments  from  the  tongue  to  the  epiglottis 
cartilage,  to  be  hereafter  described  ;  for  that  cartilage  is  attached 
by  ligaments  to  the  os  hyoides. 

The  tongue  is  thin  at  its  commencement  at  the  os  hyoides ; 
but  it  soon  increases  in  thickness.  The  muscular  fibres  in  its 
composition  have  been  considered  as  intrinsic,  or  belonging 
wholly  to  its  internal  structure  ;  and  extrinsic,  or  existing  in 
part  outside  of  this  structure.  The  lingualis  muscles  are 
intrinsic  (see  page  316)  :  they  are  situated  near  the  under  sur- 
face of  the  tongue,  one  on  each  side,  separated  from  each  other 
by  the  genio-hyo-glossi  muscles,  and  extending  from  the  basis 
of  the  tongue  to  its  apex.  These  muscles  can  be  easily  traced  as 
above  described  :  but  there  are  also  many  fibres  in  the  structure 
of  the  tongue,  which  seem  to  pass  in  every  direction,  and  of 
course  are  different  from  those  of  the  linguales  muscles.  To 
these  two  sets  of  fibres  are  owing  many  of  the  immensely 
varied  motions  of  the  different  parts  of  the  tongue. 

— According  to  Gerdy,  (whose  researches  on  this  subject 
have  been  approved  by  Ribes  and  Breschet,)  the  structure  of 
the  tongue  consists  of  the  mucous  membrane  forming  its  outer 
coat,  of  a  peculiar  yellow  lingual  tissue '  which  forms  the  liga- 
ment by  which  it  is  attached  to  the  os  hyoides  and  is  extended 
along  the  middle  line  of  the  tongue  to  form  a  sort  of  raphe  for 
the  attachment  of  the  transverse  muscular  fibres,  and  of  the 
intrinsic  and  extrinsic  muscles  ;  it  is  mixed  up  with  some  delicate 
cellular  and  adipose  tissue.  The  intrinsic  muscles  consist,  1st, 
of  a  superficial  lingual  muscle ;  2d,  of  two  deep-seated,  all  of 


464  STRUCTURE  OF  THE  TONGUE. 

which  are  longitudinal  ;  3d,  of  transverse  muscular  fibres, 
reunited  at  the  raphe,  in  the  middle  line  of  the  tongue  ;  4th,  of 
some  vertical  fibres  which  are  inserted  on  the  lower  surface  of 
the  mucous  membrane.  The  ligament  from  the  os  hyoides 
extended  along  the  middle  line  of  the  tongue,  Blandin  calls  the 
lingual  cartilage.  The  evidence  in  favor  of  its  cartilaginous 
nature,  is  not  very  satisfactory  in  man.  The  epidermis  of  the 
tongue,  which  is  much  thicker  than  that  of  other  portions  of  the 
mouth,  forms,  according  to  Blandin,  a  sheath  open  at  top,  round 
the  sensitive  papilla,  which  protects  them  when  the  tongue 
acts  as  an  instrument  of  mastication,  and  through  which  the 
papillae  protrude,  to  come  fully  in  contact  with  the  sapid  sub- 
stance when  tumefied  or  erected  by  the  gustatory  excitement. — 

In  addition  to  these,  are  the  extrinsic  muscles,  which  origi- 
nate from  the  neighboring  parts,  and  are  inserted  and  continued 
into  the  substance  of  the  tongue.  See  fig.  122. 

Among  the  most  important  of  the  muscles,  are  those  which 
proceed  from  the  chin,  or  the  genio-hyo-glossi.  They  are  in 
contact  with  each  other ;  their  fibres  radiate  from  a  central 
point  on  the  inside  of  the  chin,  and  are  inserted  into  the  middle 
of  the  lower  surface  of  the  tongue  :  the  insertion  commencing 
at  a  short  distance  from  its  apex,  and  continuing  to  its  base. 

As  the  genio-hyo-glossi  muscles  have  a  considerable  degree 
of  thickness,  they  add  much  to  the  bulk  of  the  tongue  in  the 
middle  of  the  posterior  parts  of  it. 

The  hyo-glossi  and  the  stylo-glossi,  being  continued  into  the 
posterior  and  lateral  parts,  contribute  also  to  the  bulk  of  these 
parts. 

The  tongue,  thus  composed  and  connected,  lies,  when  at 
rest,  on  the  mylo-hyoidei  muscles  ;  and  the  space  between  it 
and  these  muscles  is  divided  into  two  lateral  parts  by  the  above 
described  genio-hyo-glossi.  In  the  space  above  mentioned,  is 
a  small  salivary  gland,  of  an  irregular  oval  form  ;  the  greatest 
diameter  of  which  extends  from  before  backwards,  and  its 
«dges  present  outwards  and  inwards.  It  has  several  excretory 
ducts,  the  orifices  of  which  form  a  line  on  each  side  of  the 
tongue.  This  gland  is  very  prominent  under  the  tongue ;  and 


PAPILLAE    OF    THE  TONGUE.  465 

when  the  tongue  is  raised  it  is  particularly  conspicuous :  it  is 
called  the  Sublingual. 

The  lining  membrane  of  the  mouth  continues  from  the  inside 
of  the  alveoli  of  the  lower  jaw,  which  it  covers,  over  the  sublin- 
gual  glands  to  the  lower  surface  of  the  tongue.  In  this  situa- 
tion it  is  remarkably  thin ;  but,  as  it  proceeds  to  the  upper 
surface  of  the  tongue,  its  texture  changes  considerably,  and  on 
this  surface  it  constitutes  the  organ  of  taste. 

The  upper  surface  of  the  tongue,  although  it  is  continued 
from  the  thin  membrane  above  described,  is  formed  by  a 
rough  integument  which  consists,  like  the  skin,  of  three  lamina. 
The  cuticle  is  very  thin ;  and  under  it,  the  rete  mucosum*  is 
thicker  and  softer  than  in  other  places. 

The  true  skin  here  abounds  with  eminences  of  various  sizes 
and  forms,  all  of  which  are  denominated  Papilla.  The  largest 
of  these  are  situated  on  the  posterior  part  of  the  tongue,  and 
are  so  arranged  that  they  form  an  angle  rather  acute,  with  its 
point  backwards.  They  are  commonly  nine  in  number :  they 
resemble  an  inverted  cone,  or  are  larger  at  their  head  than  their 
basis.  They  are  situated  in  pits  or  depressions,  to  the  bottoms 
of  which  they  are  connected.  In  many  of  them  there  are 
follicles,  or  perforations,  which  have  occasioned  them  to  be 
regarded  as  glands.  They  are  called  Papilla  Maxima,  or 
Capitata. 

The  papillae,  next  in  size,  are  denominated  fungiform  by 
some  anatomists,  and  Media  or  Semilenticulares  by  others. 
They  are  nearly  cylindrical  in  form,  with  their  upper  extremi- 
ties regularly  rounded.  They  are  scattered  over  the  upper 
surface  of  the  tongue,  in  almost  every  part  of  it,  at  irregular 
distances  from  each  other. 

The  third  class  are  called  conoidal  or  villous.  They  are 
very  numerous,  and  occupy  the  greatest  part  of  the  surface  of 
the  tongue.  Although  they  are  called  conoidal,  there  is  a  great 

*  M.  Bichat  appears  to  have  had  doubts  whether  the  real  rete  mucosum 
existed  here.  He  says  that  he  could  only  perceive  a  decussation  of  vessels  in 
the  intervals  of  the  papillae,  which,  as  he  supposes,  occasioned  the  florid  color 
of  the  tongue. 


-466  PAPILLA    OF    THE    TONGUE. 

difference  in  their  form ;  many  of  them  being  irregularly  angular 
and  serrated  as  well  as  conical. 

Soemmering  and  other  German  anatomists  consider  the 
smallest  papillae  as  a  fourth  class,  which  they  call  the  filiform: 
these  lie  between  the  others. 

It  is  probable  that  these  papillae  are  essential  parts  of  the 
organ  of  taste ;  and  their  structure  is  of  course  an  interesting 
object  of  inquiry. 

The  nerves  of  the  tongue  have  been  traced  to  the  papillae, 
and  have  been  compared  by  some  anatomists  to  the  stalk  of 
the  apple,  while  the  papillae  resembled  the  fruit ;  but  their 
ultimate  termination  does  not  appear  to  have  been  ascer- 
tained.* 

— The  papillae  maximae  or  capitatae,  are  supplied,  accor- 
ding to  Cloquet,  by  filaments  from  the  glosso-pharyngeal 
nerve,  the  fungiformes  by  filaments  from  the  fifth.  The 
papillae  maximae  appear  to  consist  only  of  a  collection  of 
mucous  follicles,  which  differ  only  from  those  of  the  soft  palate 
and  lips,  by  standing  out  more  in  relief. 

— The  follicles  of  each  papilla  open  occasionally  upon  the  side; 
several  open  by  a  common  orifice  at  the  top  of  the  papilla, 
which  is  often  very  visible  to  the  naked  eye,  as  a  little  reddish 
point.  Weber  succeeded  in  injecting  this  orifice  with  mercury, 
and  found  it  led  to  a  central  cavity  irregularly  divided  by  septae 
into  cells,  visible  to  the  naked  eye,  having  some  resemblance 
to,  but  much  larger  than  those  of  the  parotid.  Other  mucous 
follicles  of  a  simpler  kind  are  spread  over  the  whole  surface  of 
the  tongue  between  the  smaller  papillae.  Some  are  mere 
small  pouches,  opening  by  simple  orifices,  without  canals. 
Others  are  more  complicated,  and  according  to  Weber,  who 
filled  them  with  mercury,  have  ducts  three  or  four  lines  in 
length,  which  run  down  between  the  muscular  fibres  of  the 

*  In  the  explanation  of  the  plates,  referred  to  in  the  following  sentence, 
Soemmering  observes,  that  when  the  fibrillaB  of  the  lingual  nerve  of  the  fifth 
pair  are  traced  to  the  papillae  of  the  second  class,  they  swell  out  into  a  conical 
form ;  and  these  nervous  cones  are  in  such  close  contact  with  each  other,  that 
the  point  of  the  finest  needle  could  not  be  insinuated  into  the  papillae  without 
touching  a  nerve. 


BLOOD-VESSELS  OF  THE  TONGUE.  467 

tongue,  to  terminate  in  little  flattened  sacs  divided  into  several 

cells,  and  having  sometimes,  a  diameter  of  three  lines. 

— From    all    these    follicles,  comes    that   profusion    of  muoous 

secretion,  which  we  see  covering  the  tongue  in  diseases. 

— He  describes    the   sebaceous   glands  of    the   skin    as  being 

analogous  in  structure  to  these  follicles,  as  well  as  those  of  the 

trachea  and  of  the  inside  of  the  lips  and  cheeks. — 

Soemmering  has  lately  published  some  elegant  engraved 
copies  of  drawings  of  these  papillae,  when  they  were  magnified 
twenty-five  times ;  from  which  it  appears  that  a  very  large 
number  of  vessels,  particularly  of  arteries,  exist  in  them. 
These  vessels  are  arranged  in  a  serpentine  direction,  and  are 
prominent  on  the  surface ;  but  they  appear  doubled,  and  the 
most  prominent  part  is  the  doubled  end. — This  arrangement 
of  vessels  is  perceptible  on  the  sides  of  the  tongue,  as  well  as 
on  the  papillae. — 

Behind  the  large  papillae  is  a  foramen,  first  described  by 
Morgagni,  and  called  by  him  Foramen  Cwcum.  It  is  the 
orifice  of  a  cavity  which  is  not  deep ;  the  excretory  ducts  of 
several  mucous  glands  open  into  it. 

On  the  upper  surface  of  the  tongue,  a  groove  is  often  to  be 
seen,  which  is  called  the  linea  mediana,  and  divides  it  into  two 
equal  lateral  parts.*  Below,  the  lining  membrane  of  the  mouth, 
as  it  is  continued  from  the  lower  jaw  to  the  tongue,  forms  a 
plait,  which  acts  as  a  ligament,  and  is  called  the  frcenum  lingua. 
It  is  attached  to  the  middle  of  the  tongue,  %at  some  distance 
behind  the  apex.  t 

The  tongue  is  well  supplied  with  blood-vessels,  which  are 
derived  Irom  the  lingual  branch  of  the  external  carotid  on 
each  side.  This  artery  passes  from  the  external  carotid, 
upwards,  inwards,  and  forwards,  to  the  body  of  the  tongue. 
In  this  course  it  sends  off  several  small  arteries  to  the  contig- 
uous parts,  and  one  which  is  spent  about  the  epiglottis  and  the 
adjoining  parts,  called  the  Dorsalis  Lingua.  About  the 
anterior  edge  of  the  hyo-glossus  muscle,  it  divides  into  two 

*  This  groove  indicates  the  position  of  the  middle  raphe  of  Gerdy. 


468  BLOOD-VESSELS  OF  THE  TONGUE. 

large  branches:  one  of  which,  called  the  Sublingual^  passes 
under  the  tongue  between  the  genio-hyo-glossus  and  the  sub- 
lingual  gland,  and  extends  near  to  the  symphysis  of  the  upper 
jaw  ;  sending  branches  to  the  sublingual  gland,  to  the  muscles 
under  the  tongue,  to  the  skin,  and  the  lower  lip.  The  other  is 
in  the  substance  of  the  tongue,  on  the  under  side  near  the  sur- 
face, and  extends  to  the  apex. 

The  veins  of  this  organ  are  not  so  regular  as  the  arteries : 
they  communicate  with  the  external  jugular,  and  some  of  them 
are  always  very  conspicuous  under  the  tongue  :  these  are  called 
ranular. 

It  is  to  be  observed,  that  the  vessels  on  each  side  have  but 
little  connexion  with  each  other ;  for  those  of  one  side  may  be 
injected  while  the  others  continue  empty. 

The  tongue  is  also  well  supplied  with  nerves,  and  derives 
them  from  three  different  sources  on  each  side,  namely,  from  the 
fifth,  the  eighth,  and  ninth  pairs  of  the  head. 

The  lingual  portion  of  the  third  branch  of  the  fifth  pair  pass- 
ing under  the  tongue,  enters  its  substance  about  the  middle,  and 
forms  many  minute  branches,  which  pass  to  the  papillae  of  the 
forepart  of  the  tongue. 

The  glosso-pharyngeal  portion  of  the  eighth  pair,  sending  off 
several  branches  in  its  course,  passes  to  the  tongue  near  its  basis, 
and  divides  into  many  small  branches,  which  are  spent  upon  the 
sides  and  middle  of  the  root  of  the  tongue,  and  also  upon  the 
large  papillae. 

The  ninth  pair  of  nerves  are  principally  appropriated  to  the 
tongue.  They  pass  on  each  side  to  the  most  fleshy  part  of  it, 
and  after  sending  one  branch  to  the  mylo-hyoideus,  and  another 
to  communicate  with  the  lingual  branch  of  the  fifth  pair,  they 
are  spent  principally  upon  the  genio-glossi,  and  linguales 
muscles. 

The  tongue  answers  a  threefold  purpose.  It  is  the  princi- 
pal organ  of  taste.  It  is  a  very  important  agent  in  the  articu- 
lation of  words,  and  it  assists  in  those  operations  upon  our  food, 
which  are  performed  in  the  mouth. 


PAROTID    GLAND.  469 

The  Salivary   Glands. 

The  salivary  glands  have  such  an  intimate  connexion  with 
the  mouth  that  they  may  be  described  with  it.* 

There  are  three  principal  glands  on  each  side :  the  Parotid, 
Submaxillary,  and  the  SublinguaL  They  are  of  a  whitish  or 
pale  flesh  color,  and  are  composed  of  many  small  united  masses 
or  lobuli,  each  of  which  sends  a  small  excretory  duct  to  join 
similar  ducts  from  the  other  lobuli,  and  thereby  form  the  great 
duct  of  the  gland. 

The  Parotid  is  much  larger  than  the  other  glands.  It 
occupies  a  large  portion  of  the'  vacuity  between  the  mastoid 
process  and  the  posterior  parts  of  the  lower  jaw.  It  extends 
from  the  ear  and  the  mastoid  process  over  a  portion  of  the 
masseter  muscle,  and  from  the  zygoma  to  the  basis  of  the  lower 
jaw.  Its  name  is  supposed  to  be  derived  from  two  Greek 
words  which  signify  contiguity  to  the  ear.  It  is  of  a  firm  con- 
sistence. It  receives  branches  from  the  external  carotid  artery 
and  from  its  facial  branch. 

From  the  anterior  edge  of  this  gland,  rather  above  the  middle, 
the  great  duct  proceeds  anteriorly  across  the  masseter  muscle  ; 
and,  after  it  has  passed  over,  it  bends  inward  through  the  adipose 
matter  of  the  cheek  to  the  buccinator  muscle,  which  it  perforates 
obliquely,  and  opens  on  the  inside  of  the  cheek  opposite  to  the 
interval  between  the  second  and  third  molar  teeth  of  the  upper 
jaw.  The  aperture  of  the  duct  is  rather  less  than  the  general 
diameter  of  it,  and  this  circumstance  has  the  effect  of  a  valve. 
When  the  duct  leaves  the  parotid,  several  small  glandular 
bodies  called  sociae  parotidis,  are  often  attached  to  it,  and  their 
ducts  communicate  with  it.  The  main  duct  is  sometimes  called 
ductus  stenoMyinus,  after  Steno,  who  first  described  it. 

When  the  mouth  is  opened  wide,  as  in  gaping,  there  is  often 
a  jet  of  saliva  from  it  into  the  mouth. 

The  parotid  gland  furnishes  the  largest  proportion  of  saliva. 

It  covers  the  nerve  called  Portio  Dura,  after  it  has  emerged 
from  the  foramen  stylo-mastoideum. 

*  For  a  further  account  of  glands,  see  General  Anatomy  of  Glandular 
System. 

40 


470         ULTIMATUM  STRUCTURE  OF  THE  SALIVARY  GLANDS. 

.  «. 

— This  nerve  after  being  covered  a  short  distance  by  the 
gland,  enters  its  substance,  and  forms  there  the  plexus  called 
pas  anserinus,  so  as  to  leave  a  portion  of  the  gland  on  the  inner 
face  of  the  nerve.  The  external  carotid  artery  likewise  traverses 
the  gland  and  is  situated  rather  more  exteriorly  than  the  nerve, 
so  as  to  leave  about  one-third  of  the  gland  on  its  inner  face. 
Branches  from  the  artery* are  sent  off  in  various  directions 
as  it  traverses  the  gland,  to  the  face,  and  to  the  structure  of  the 
gland  itself. 

— The  duct  of  Steno,  is  very  feebly  attached  to  the  surrounding 
parts,  and  is  accompanied  by  many  branches  of  the  middle 
division  of  the  facial  nerves,  and  some  small  arteries  which 
supply  its  walls  ;  it  is  covered  only  by  the  skin,  some  adipose 
tissue,  by  some  fibres  of  the  platysma  myoides,  and  the 
zygomaticus  major  which  crosses  it  obliquely.  Its  general 
diameter  is  about  a  line ;  and  it  is  very  distensible.  It  will  be 
found,  according  to  the  rule  laid  down  by  Dr.  Physick, 
under  a  line  drawn  from  the  lobe  of  the  ear,  to  the  tip  of  the 
nose. 

119.  — The  duct  is  composed  of  two  coats,  one, 
external,  white,  fibrous,  and  resisting;  the 
other,  internal,  is  a  mucous  membrane,  con- 
tinuous with  the  lining  membrane  of  the 
mouth,  and  appears  to  differ  from  it  only  in 
being  paler. 

— Fig.  119,  is  a  microscopical  representation 
of  the  structure  of  a  portion  of  the  parotid 
gland  of  a  young  infant,  after  it  had  been 
minutely  injected  with  mercury  from  the  duct  of  Steno,  by  E. 
H.  Weber,  of  Leipzic.  The  small  figure,  to  the  right,  is  the 
natural  size  of  the  piece  magnified,  in  which  the  salivary  ducts 
were  filled  with  the  fluid  to  their  very  terminations.  A  branch 
of  the  salivary  duct,  is  seen  on  the  right  margin  of  this  figure, 
ramifying  like  the  branch  of  a  tree.  These  ramifications  never 
anastomose  together,  and  are  of  much  greater  size  than  the 
capillary  blood-vessels.  Each  ramification,  at  its  termination, 
resolves  itself  into  cells  densely  compacted  together,  like  a 


THE  SUBMAXILLARY  GLAND.  471 

bunch  of  grapes  upon  its  stem,  a,  a,  a.  Some  of  the  cells 
open  by  a  minute  excretory  tube  directly  into  the  salivary 
duct.  In  other  instances  some  of  the  ducts  of  the  cells  uffite 
into  a  common  tube,  before  entering  the  salivary  duct.  The 
cells  are  not  round,  and  vary  among  themselves  in  regard  to 
size. 

— The-  average  diameter  of  these  cells,  measured  by  a  micro- 
meter, were  found  by  Weber,  to  be  the  ^gth  part  of  an  inch, 
which  he  finds  to  be  three  times  greater  than  that  of  the  most 
delicate  sanguineous  vessels.  The  cellular  structure  of  the 
parotid,  seems  therefore  to  be  very  analogous  to  the  cellular 
structure  of  the  lungs  discovered  by  Soemmering  and  Reisseis- 
sen,  the  cells  of  the  lungs,  however,  being  five  or  six  times 
larger  than  those  of  the  parotid.  The  elaborate  researches  of 
Weber  and  Muller,  have  shown  also  that  this  is  the  common 
mode  of  termination  of  the  excretory  ducts  in  the  different 
glands  of  the  body ;  viz.  that  they  terminate  in  closed  cells, 
upon  which  ramify  the  delicate  secretory  capillary  vessels. — 

The  second  gland  is  called  the  Submaxillary.  It  is  much 
smaller  than  the  parotid,  and  rather  round  in  form.  It  is 
situated  immediately  within  the  angle  of  the  lower  jaw, 
between  it  on  the  outside,  and  the  tendon  of  the  digastric 
muscle  and  the  ninth  pair  of  nerves  internally.  Its  posterior 
extremity  is  connected  by  cellular  membrane  to  the  parotid 
gland  ;  its  anterior  portion  lies  over  a  part  of  the  mylo-hyoideus 
muscle  ;  and  from  it  proceeds  the  excretory  duct,  which  is  of 
considerable  length,  and  passes  between  the  mylo-hyoideus 
and  genio-glossus  muscles  along  the  under  and  inner  edge  of 
the  sublingual  gland.  In  this  course  the  duct  is  sometimes 
surrounded  with  small  glandular  bodies,  which  seem  to  be 
appendices  to  the  sublingual  gland.  It  terminates  under  the 
tongue,  on  the  side  of  the  fraenum  linguae,  by  a  small  orifice 
which  sometimes  forms  a  papilla.*  (See  fig.  118,  p.  454.) 

*  Lassus  informs  us  that  Oribases,  afterwards  all  the  Arabians,  and  subse- 
quently Guy  De  Chauliac,  Lanfranc,  Achillini,  Berenger  De  Carpi,  Charles 
Etienne,  Casserius  and  several  others  have  given  the  description  of  these  salivary 
ducts  ;  notwithstanding  which,  Wharton,  a  physician  of  London,  attributed  to 
himself  the  discovery  of  them  on  the  bullock,  in  1656. — u. 


472  SUBLINGUAL      GLAND. 

The  orifice  is  often  smaller  than  the  duct ;  in  consequence  of 
which,  obstruction  frequently  occurs  here,  and  produces  the 
disease  called  ranula. 

The  Sublingual  gland,  which  has  already  been  mentioned, 
lies  so  that,  when  the  tongue  is  turned  up,  it  can  be  seen  pro- 
truding into  the  cavity  of  the  mouth,  and  covered  by  the  lining 
membrane,  which  seems  to  keep  it  fixed  in  its  place.  It  lies 
upon  the  mylo-hyoideus,  by  the  side  of  the  genio-hyoideus  ; 
and  is  rather  oval  in  form,  and  flat.  Its  greatest  length  is  from 
before  backwards  ;  its  position  is  rather  oblique,  one  edge  being 
placed  obliquely  inwards  and  upwards,  and  the  other  outwards 
and  downwards.  It  has  many  short  excretory  ducts,  which 
open  by  orifices  arranged  in  a  line  on  each  side :  they  are 
discovered  with  difficulty  on  account  of  their  small  size,  and 
sometimes  amount  to  eighteen  or  twenty  in  number.  In  some 
few  instances,  this  gland  sends  off  a  single  duct,  which  com- 
municates with  the  duct  of  the  submaxillary  gland. 

— The  duct  of  the  Submaxillary  gland  is  called  the  duct  of 
Wharton,  (ductus  Whartonionus)  from  an  English  anato- 
mist who  first  described  it.  It  is  accompanied  in  nearly  the 
whole  of  its  course  by  the  lingual  branch  of  the  fifth  pair  of 
nerves. 

— The  usual  arrangement  of  the  ducts  of  the  sublingual 
gland  is  as  follows  :  six  or  eight  run  from  the  upper  part  of  the 
gland,  to  open  by  the  side  of  the  fraenum  linguae.  Five  or  six 
others  proceed  from  its  sides  to  open  separately  in  the  mucous 
membrane  above  the  gland.  Several  open  into  the  duct  of 
Wharton  which  runs  by  the  side  of  the  gland  ;  these  most 
frequently  unite  to  form  a  single  duct,  called  the  duct  of  Bar- 
tholinus,  or  duct  of  Rivinus.  This  I  have  frequently  succeeded 
in  distending  with  mercury  from  the  duct  of  Wharton. 
— The  structure  and  office  of  these  salivary  glands  appear  the 
same,  and  not  unfrequently  a  slight  continuation  of  structure  is 
observed  at  the  two  extremities  of  the  submaxillary  gland. — 

The  salivary  fluid  secreted  by  these  glands  is  inodorous, 
insipid,  and  limpid,  like  water ;  but  much  more  viscid,  and  of 
greater  specific  gravity.  Water  constitutes  at  least  four-fifths 


OBSERVATIONS  ON  THE  TONGUE.  473 

of  its  bulk  ;  and  animal  mucus  one  half  of  its  solid  contents. 
It  also  contains  some  albumen  ;  and  several  saline  substances ; 
as  the  muriate  of  soda,  and  the  phosphates  of  lime,  of  soda,  and 
of  ammonia. 

It  is  probable  that  this  fluid  possesses  a  solvent  power  with 
respect  to  the  articles  of  food. 

There  are  small  glandular  bodies,  situated  between  the 
masseter  and  buccinator  muscles,  opposite  to  the  last  molar 
tooth  of  the  upper  jaw,  whose  nature  is  not  well  understood  : 
they  are  called  Glandula  molares.  They  are  believed  to  be 
mere  mucous  glands. 

The  motions  of  the  tongue  are  very  intelligible  to  a  person  who  has  a  prepara- 
tion of  the  lower  jaw  before  him,  with  the  tongue  in  its  natural  situation,  and 
the  muscles  which  influence  it,  properly  dissected.  Its  complicated  move- 
ments will  appear  the  necessary  result  of  the  action  of  those  muscles  upon  it, 
and  the  os  hyoides  ;  and  also  upon  the  larynx,  with  which  the  os  hyoides  is 
connected.  The  muscular  fibres  of  the  tongue  itself  are  also  to  be  taken 
into  this  view,  as  they  act  a  very  important  part. 

Although  the  tongue  appears  very  necessary,  in  a  mechanical  point  of  view,  to 
the  articulation  of  many  words,  yet  there  are  cases  where  it  has  been  entirely 
deficient,  in  which  the  parties  thus  affected,  have  been  able  to  speak  very  well 
in  general,  as  well  as  to  distinguish  different  tastes.* 

The  tongue  is  also  a  very  delicate  organ  of  touch. — We  can  perceive  the  form 
of  the  teeth,  and  the  state  of  the  surface  of  the  mouth,  more  accurately  by 
the  application  of  the  tongue  than  of  the  fingers. 

On  the  three  nerves  which  go  to  the  tongue,  it  is  generally  supposed  that  the 
lingual  portion  of  the  third  branch  of  the  fifth  pair  is  most  immediatety  con- 
cerned in  the  function  of  tasting,  as  it  passes  to  the  front  part  of  the  surface 
of  the  tongue.  The  glosso-pharyngeal  are  probably  concerned  in  the  same 
function  on  the  posterior  part,  while  the  ninth  pair  of  nerves  seems  principally 
spent  upon  the  muscular  parts  of  the  organ. 

It  is  obvious  that  the  tongue  is  most  copiously  supplied  with  nerves.  This 
probably  accounts  for  the  great  facility  of  its  motions,  and  the  power  of  con- 
tinuing them. 

*  There  is  a  very  interesting  paper  on  this  subject,  in  the  Memoirs  of  the  Academy  of 
Sciences  for  the  year  1718,  by  Jussieu  ;  in  which  he  describes  the  case  of  a  female  fifteen 
years  old,  examined  by  himself,  who  was  born  without  a  tongue.  In  this  paper  he  refers  to 
another  case,  described  by  Rolland,  a  surgeon  of  Saumur,  of  a  boy  nine  years  old,  whose 
tongue  was  destroyed  by  gangrene.  In  each  of  these  cases  the  subject  was  able  to  articulate 
very  well,  with  the  exception  of  a  few  letters ;  and  also  enjoyed  the  sense  of  taste. 


40* 


474  OF    THE    THROAT. 


CHAPTER  XIV. 

OF  THE  THROAT. 

To  avoid  circumlocution,  the  word  throat  is  used  as  a 
general  term  to  comprehend^  the  structure  which  occurs  behind 
the  nose  and  mouth,  and  above  the  ossophagus  and  trachea. 
This  structure  consists, 

1st.  Of  the  parts  immediately  behind  the  mouth,  which  con- 
stitutes the  Isthmus  of  the  Fauces  : 

2d.  Of  the  parts  which  form  the  orifice  of  the  windpipe,  or 
the  Larynx  ; — and 

3d.  Of  the  muscular  bag,  which  forms  the  cavity  behind  the 
nose  and  mouth,  that  terminates  in  the  oesophagus  or  the 
Pharynx. 

Of  the  Isthmus  oj  the  Fauces. 

In  the  back  part  of  the  mouth,  on  each  side,  are  to  be  seen 
the  two  ridges  or  half  arches,  passing  from  the  soft  palate  to 
the  root  of  the  tongue,  (see  fig.  118,  p.  454,)  formed  by  plaits 
of  the  mucous  membrane,  containing  muscular  fibres.  The 
anterior  plait,  which  contains  the  muscle  called  Constrictor 
Isthmi  Faucium,  passes  directly  from  the  side  of  the  root  of 
the  tongue  to  the  palate,  and  terminates  near  the  commence- 
ment of  the  uvula.  The  posterior  plait  runs  from  the  palate 
obliquely  downwards  and  backwards,  as  it  contains  the  palato- 
pharyngeus  muscle,  which  passes  from  the  palate  to  the  upper 
and  posterior  part  of  the  thyroid  cartilage. 

In  the  triangular  space  between  these  ridges  is  situated  a 
glandular  body,  called  the  Tonsil  or  Amygdala.*  This  gland 

*  It  is  named  amygdala,  from  its  resemblance  in  form  and  appearance  to  an 
almond  covered  by  its  shell.  The  exterior  or  adhering  surface  of  the  tonsil 
gland  is  connected  by  the  means  of  cellular  tissue  to  the  superior  constrictor 
muscle  of  the  pharynx. 

The  internal  carotid  artery  is  situated  behind  and  to  the  outer  side  of  the 
tonsil,  and  separated  from  it  only  by  the  constrictor  muscle,  and  cellular  tissue. 

It  has  been  wounded  in  opening  abscesses  of  the  tonsils,  when  the  cutting 
instrument  has  been  inclined  too  much  outwards  and  backwards. — r. 


TONSILS. EPIGLOTTIS.  475 

has  an  oval  form,  its  longest  diameter  extending  from  above 
downwards.  *  Its  surface  is  rather  convex,  its  natural  color  is 
a  pale  red.  On  its  surface  are  the  large  orifices  of  many  cells 
of  considerable  size,  which  exist  throughout  the  gland.  These 
cells  often  communicate  with  each  other,  so  that  a  probe  can 
be  passed  in  at  one  orifice  and  out  at  the  other. 

Into  these  cells  open  many  mucous  ducts,  which  discharge 
in  part  the  mucus  of  the  throat,  for  the  purpose  of  lubricating 
the  surface,  and  facilitating  the  transmission  of  food. 

— In  its  healthy  state,  the  free  surface  of  the  tonsil  glands, 
are  a  little  below  the  level  of  the  two  half  arches  of  each  side. 
— But  when  their  cells  are  distended  by  inflammation,  or  effaced 
by  granulations,  as  in  tonsillitis,  they  sometimes  project  beyond 
the  half  arches  so  as  nearly  or  quite  to  meet  in  the  middle 
line. — 

The  epiglottis,  or  fifth  cartilage  of  the  larynx,  is  situated  at 
the  root  of  the  tongue,  in  the  middle,  between  the  tonsils.  The 
part  which  is  in  sight  is  partly  oval  in  form,  and  of  a  whitish 
color.  Its  position,  as  respects  the  tongue,  is  nearly  perpen- 
dicular, and  its  anterior  surface  rather  convex. 

The  mucous  membrane  continued  from  the  tongue  over  the 
epiglottis  is  so  arranged  that  it  forms  a  plait,  which  extends 
from  the  middle  of  the  root  of  the  tongue  along  the  middle  of 
the  anterior  surface  of  the  epiglottis,  from  its  base  upwards. 

On  each  side  of  this  plate  or  fraenum,  at  the  junction  of  the 
surfaces  of  the  tongue  and  of  the  epiglottis  there  is  often  a  de- 
pression, in  which  small  portions  of  food  sometimes  remain  ; 
and  a  small  fraenum,  similar  to  that  above  described,  is  sometimes 
seen  on  the  outside  of  each  of  these  cavities. 

The  epiglottis  is  situated  immediately  before  the  opening 
into  the  larynx. 

The  above  described  parts  can  be  well  ascertained  in  the 
living  subject,  by  a  person  who  has  a  general  knowledge  of  the 
structure.  Thus,  looking  into  the  mouth,  with  the  tongue  de- 
pressed, the  uvula  and  soft  palate  are  in  full  view  above,  and 
the  epiglottis  is  very  perceptible  below ;  while  the  two  ridges 


476  THE   LARYNX. 

or  lateral  half  arches  can  be  seen  on  each  side,  with  the  tonsil 
between  them. 

Of  the  Larynx.  f 

— The  larynx  is  situated  immediately  below  the  os  hyoides, 
and  is  continuous  at  its  inferior  part  with  the  trachea,  to  which 
it  is  attached,  like  a  capital  upon  a  column.  It  serves  a  double 
purpose  ;  that  of  a  tube  for  the  introduction  of  air  into  the 
lungs  ;  and  that  of  a  very  complicated  apparatus  for  the  pro- 
duction of  the  voice. 

— It  is  composed  of  cartilages  which  form  its  frame-work,  liga- 
ments and  synovial  capsules  which  unite  the  cartilages  together, 
muscles  to  put  them  into  motion,  and  an  exquisitely  sensitive 
mucous  membrane,  that  lines  the  whole  of  its  interior.  It  is 
larger  and  much  more  prominent  in  males  than  females,  and 
undergoes  a  rapid  and  remarkable  degree  of  development, 
both  in  regard  to  size  and  energy  of  function  at  the  period  of 
puberty. — 

In  this  structure  are  five  cartilages,  upon  which  its  form  and 
strength  depends,  namely,  the  Cricoid,  the  Thyroid,  the  two 
Arytenoid,  and  the  Epiglottis.  These  cartilages  are  articulated 
to  each  other,  and  are  supplied  with  muscles  by  which  certain 
limited  motions  are  effected. 

The  basis  of  the  structure  is  a  cartilaginous  ring,  called  the 
cricoid  cartilage,  and  which  may  be  considered  as  the  com- 
mencement of  the  windpipe. 

It  may  be  described  as  an  irregular  section  of  a  tube :  its 
lower  edge  connected  with  the  windpipe,  being  nearly  hori- 
zontal when  the  body  is  erect ;  and  the  upper  edge  very  oblique, 
sloping  from  before,  backwards  and  upwards  ;  in  consequence 
of  this,  it  has  but  little  depth,  before,  but  is  eight  or  nine  lines 
deep  behind. 

— In  front,  and  upon  each  side  of  the  middle  line  there  is  a 
depression,  in  which  arises  the  two  crico-thyroid  muscles.  Upon 
each  side,  and  near  its  upper  and  outer  surface,  there  is  a 
smooth  convex  facet,  upon  which  is  articulated,  the  corres- 


CRICOID    CARTILAGE. THYROID  CARTILAGE.  477 

ponding  facet  of  the  inferior  cornua  of  the  thyroid  cartilage. 
Posteriorly  are  two  slight  vertical  depressions,  to  which  are 
attached  the  crico-arytenoidei  postici  muscles.  Its  internal  fcrce 
is  covered  by  mucous  membrane.  Its  superior  border  gives 
attachment  in  front  to  the  crico-thyroid  membrane,  on  the  sides 
to  the  lateral  crico-arytenoid  muscles,  and  posteriorly  presents 
a  little  notch,  limited  by  two  convex  facets  upon  which  are 
articulated  the  arytenoid  cartilages. — 

The  Thyroid  cartilage  is  a  single  plate,  bent  in  such  manner 
that  it  forms  an  acute  angle  with  two  similar  broad  surfaces 
on  each  side  of  it.  It  is  so  applied  to  the  cricoid  cartilage,  that 
the  lower  edge  of  the  angular  part  is  at  a  small  distance  above 
the  front  part  of  that  cartilage,  and  connected  to  it  by  ligamen- 
tous  membrane ;  while  its  broad  sides  are  applied  to  it  later- 
ally, and  thus  partially  enclose  it. 

The  upper  edge  of  the  angular  part  of  the  thyroid  cartilage 
forms  a  notch  ;  and  the  natural  position  of  the  cartilage  is  such, 
that  this  part  is  very  prominent  in  the  neck ;  it  is  called  the 
Pomum  Adami. 

Both  the  upper  and  lower  edges  of  the  thyroid  cartilage 
terminate  posteriorly  in  processes,  which  are  called  Cornua. 
The  two  uppermost  are  longest :  they  are  joined  by  ligaments 
to  the  extremities  of  the  os  hyoides.  The  lower  and  shorter 
processes  are  fixed  to  the  cricoid  cartilage.  The  thyroid  car- 
tilage, therefore,  partly  rests  upon  the  cricoid  cartilage  below, 
and  is  attached  to  the  os  hyoides  above.  It  is  influenced  by  the 
muscles  which  act  upon  the  os  hyoides,  and  also  by  some  mus- 
cles which  are  inserted  into  itself.  It  is  moved  obliquely 
downwards  and  forwards  in  a  slight  degree  upon  the  cricoid 
cartilage,  by  a  small  muscle,  the  crico-thyroideus,  which 
arises  from  that  cartilage  and  is  inserted  into  it. 

— The  external  lateral  surface  of  the  thyroid  cartilage  is 
slightly  concave,  and  across  it,  passes  a  small  ridge  obliquely 
from  above  downwards,  and  from  behind  forwards,  which 
gives  attachment  above  to  the  thyro-hyoid  and  below  to  the 
sterno-hyoid  muscles.  The  posterior  or  inside  face  of  the 
Pomum  Adami  presents  an  entering  angle,  where  the  two 


478  ARYTENOID    CARTILAGES. 

symmetrical  sides  of  the  cartilage  meet,  and  in  which  is 
attached  the  thyro-arytenoid  muscles,  the  pedicle  of  the  epi- 
glottis and  one  end  of  the  vocal  ligaments.  The  upper  margin 
of  the  cartilage  presents  a  curved  appearance  like  that  of  the 
italic  long  /;  a  similar  curvature  is  also  observable  on  its  pos- 


terior margin.  — 


Fig.  120.*  The  ^Arytenoid  cartilages  are   two  small 

bodies  of  a  triangular  or  pyramidal  form 
anc^  slightty  curved  backward.  They  are 
placed  upon  the  upper  and  posterior  edge 
of  the  cricoid  cartilage,  near  to  each  other  ; 
their  upper  ends,  taken  together,  resem- 
ble the  mouth  of  a  pitcher  or  ewer  ;  from 
_  which  circumstance  their  name  is  derived. 

Their  bases  are  broad  ;  and  on  their  lower  surfaces  is  a  cavity, 
which  corresponds  with  the  convex  edge  of  the  cricoid  carti- 
lage, to  which  they  are  applied.  At  these  places,  a  regular 
movable  articulation  is  formed,  by  a  capsular  ligament  between 
each  of  these  cartilages  and  the  cricoid,  in  consequence  of 
which  they  can  be  inclined  backward  or  forward,  inward  or 
outward. 

From  the  anterior  part  of  each  of  these  cartilages,  near  the 
base,  a  tendinous  cord  passes  forward,  in  a  direction  which  is 
horizontal  when  the  body  is  erect,  to  the  internal  surface  of  the 
angle  of  the  thyroid.  These  ligaments  are  not  perfectly  parallel 
to  each  other  ;  they  are  nearer  before  than  behind.  The 
aperture  between  them  is  from  two  to  five  lines  wide  when  the 
muscles  are  not  in  action  ;  and  this  aperturef  is  the  orifice  of 
the  windpipe  :  for  the  exterior  space,  between  these  ligaments 
and  the  circumference  of  the  thyroid,  is  closed  up  by  mem- 


*  Vertical  section  of  the  larynx,  h,  Os  hyoides.  t,  Thyroid  cartilages,  c  c, 
Cricoid  cartilage,  a,  Arytenoid  cartilage,  v,  Ventricle  of  the  larynx,  bounded 
below  by  the  ligamenta  vocales,  and  above  by  the  superior  ligaments  of  the 
glottis,  e,  Epiglottis  cartilage,  g,  Ligamentous  attachment  of  the  tongue  to 
the  os  hyoides.  b,  Trachea  cut  off  at  the  third  ring.  The  lining  membrane  is 
left  out  in  this  section. 

f  It  forms  also  the  rima  glottidis  of  the  larynx. 


EPIGLOTTIS.  479 

brane  and  muscle.  At  a  small  distance  above  these  ligaments 
are  two  others,  which  also  pass  from  the  arytenoid  to  the  thyroid 
cartilages.  They  are  not  so  tendinous  aud  distinct  as  -the 
first  mentioned,  and  cannot  be  drawn  so  tense  by  the 
muscles  of  the  arytenoid  cartilages.  They  are  also  situated 
at  a  greater  distance  from  each  other,  and  thus  form  a  large 
aperture. 

On  the  external  side  of  the  upper  extremity  of  each  of  the 
arytenoid  cartilages,  and  nearly  in  contact  with  it,  is  a  small 
cartilaginous  body,  not  so  large  as  a  grain  of  wheat,  and 
nearly  oval  in  form.  These  are  connected  firmly  to  the  aryte- 
noid cartilages,  and  are  called  their  Appendices.*  Being  in  the 
margin  of  the  aperture  of  the  larynx,  they  have  an  effect  upon 
its  form. 

The  arytenoid  cartilages  are  the  posterior  parts  of  the  larynx. 
The  Epiglottis,  which  has  already  been  mentioned  is  the 
anterior.  When  this  cartilage  is  divested  of  its  membrane, 
it  is  oval  in  its  upper  extremity,  and  rather  angular  below, 
terminating  in  a  long  narrow  process,  which  is  like  the  stalk  of 
a  leaf. 

It  is  firmly  attached  to  the  internal  surface  of  the  angular 
part  of  the  thyroid  by  this  lower  process  ;  and,  being  placed  in 
a  perpendicular  position,  one  of  its  broad  surfaces  is  anterior — 
towards  the  tongue,  and  the  other  posterior — towards  the  opening 
of  the  windpipe. 

It  is  attached  to  the  os  hyoides  by  dense  cellular  texture  or 
ligament,  and  to  the  tongue  by  those  plaits  of  the  membrane  of 
the  mouth  which  have  been  already  described. 

It  is  elastic,  but  more  flexible  than  the  other  cartilages ;  being 
somewhat  different  in  its  structure.  Its  surface  is  perforated  by 
the  orifices  of  many  mucous  ducts. 

There  is  a  small  space  between  the  lower  part  of  this  carti- 
lage, and  the  upper  part  of  the  thyroid  and  the  ligamentous 
membrane  passing  from  it  to  the  os  hyoides.  In  this  is  a  sub- 
stance, which  appears  to  consist  of  glandular  and  of  adipose 

*  They  are  also  called  Cornicula  Laryngis,  Tubercles  of  Santorini. — p. 


480  VENTRICLE  OF  GALEN  OR  MORGAGNI. 

matter,  (see  fig.  120.)  It  is  supposed  that  some  of  the  orifices 
on  the  lower  part  of  the  epiglottis  communicate  with  this 
substance. 

— This  substance  is  a  collection  of  mucous  glands,  called 
glandules  epiglottidtz ;  the  ducts  which  arise  from  them  are 
twenty  or  thirty  in  number,  and  perforate  the, epiglottis  to  throw 
their  mucus  on  the  side  of^the  larynx. — 

In  the  erect  position  of  the  body,  the  epiglottis  is  situated 
rather  higher  up  than  the  arytenoid  cartilages,  and  at  the  dis- 
tance of  ten  or  twelve  lines  from  them. 

The  mucous  membrane  which  covers  the  epiglottis,  is 
reflected  backwards  from  the  base  of  the  tongue,  and  is 
extended  from  each  side  of  it  to  the  arytenoid  cartilages,  and 
being  continued  into  the  cavity  of  the  larynx,  as  well  as  upon 
the  general  surface  of  the  throat,  it  is  necessarily  doubled : 
this  doubling  forms  the  lateral  margins  of  the  orifice  of  the 
cavity  of  the  larynx.  In  these  folds  of  the  membrane  are  seen 
some  very  delicate  muscular  fibres,  forming  the  Aryteno-epi- 
glottideus  muscle. 

— The  epiglottis  maintains  its  vertical  position,  partly  from 
its  own  elasticity  of  structure,  and  partly  from  the  folds  of 
mucous  membrane,  reflected  to  it  from  the  tongue,  which  contain 
some  yellow  elastic  ligarnentous  fibres. — 

The  membrane  continues  down  the  cavity  of  the  larynx, 
and,  covering  the  upper  ligaments,  penetrates  into  the  vacuity 
between  them  and  the  lower  ligaments,  so  as  to  form  a  cavity 
on  each  side  of  the  larynx,  opening  between  the  two  ligaments, 
which  is  called  the  Ventricle  of  MorgagnL  The  shape  of 
each  cavity  is  oblong.  Its  greatest  length  extends  from 
behind  forward,  on  each  side  of  the  opening  into  the  windpipe 
formed  by  the  two  lower  or  principal  ligaments ;  so  that  when 
the  larynx  is  removed  from  the  subject,  upon  looking  into  it 
from  above,  you  perceive  three  apertures  :  one  in  the  middle, 
formed  by  the  two  lower  ligaments  ;  and  one  on  each  side  of 
it,  between  the  lower  and  upper  ligament,  which  is  the  orifice 
of  the  ventricle  of  Morgagn^. 
— If  a  probe  be  passed*  into  this  ventricle  of  the  larynx,  or  ven- 


VENTRICLE  OF  GALEN  OR  MORGAGNI RIMA  GLOTTIDIS.    481 

tricle  of  Morgagni,  it  will  be  found  to  pass  much  above  the  supe- 
rior thyro-arytenoid  ligament,  into  a  prolongation  of  the  cavity  of 
Fig.  121.*  the  ventricle,  which  extends  as  high  as^the 
upper  margin  of  the  thyroid  cartilage,  and 
which  has  been  called  by  Mr.  Hilton,  the 
Sacculus  Laryngis.  It  was  pointed  out 
by  Morgagni,  and  has  been  compared  by 
M.  Cruvielhier,  from  its  shape,  to  a  Phry- 
gian casque. — It  is  apt  to  escape  observation 
in  the  healthy  state.  When  death  has  taken 
place,  from  pulmonary  emphysema,  or  lar- 
yngeal  phthisis,  I  have,  on  several  occasions,  found  the  sac  so 
large  as  to  project  considerably  above  the  thyroid  cartilage. 
The  ventricle  and  its  sac,  appear  to  be  intended  for  the  supply  of 
a  lubricating  secretion  to  the  vocal  chords,  which  are  kept  in 
such  constant  action,  during  respiration  and  phonation.  The  sur- 
face of  the  cavity,  is  studded  with  sixty  or  seventy  small  follicu- 
lar  glands,  which  are  seated  in  the  submucous  tissjue,  and  give 
to  the  mucous  membrane,  when  dissected  out,  a  rough  appear- 
ance. The  greater  part  of  these  follicles  is  placed  in  the  sac, 
and  the  fluid  which  they  form,  is  directed  upon  the  rima  glottidis, 
by  two  small  folds  of  mucous  membrane,  at  the  entrance  of 
the  sacculus. — 

The  aperture  between  the  two  lower  ligaments  is  called  the 
Rima  Glottidis,  or  Chink  of  the  Glottis;  the  upper  aperture, 
formed  by4  the  fold  of  the  membrane  and  extending  from  the 
epiglottis  to  the  arytenoid  cartilages,  may  be  termed  Glottis. 

— The  folds  of  the  membrane  forming  the  upper  margin  of 
the  glottis  is  loose  and  distensible,  and  is  liable  in  laryngeal 
inflammation  to  become  oedematous  and  bag  out  so  as  to  im- 
pede respiration  to  a  great  extent,  and  even  produce  suffoca- 
tion.— 

If  the  windpipe  is  divided  near  the  larynx,  and  the  larynx 
inverted,  so  that  the  rima  glottidis  may  be  examined  from 
below,  the  structure  appears  still  more  simple:  it  resembles  a 

*  Front  view  of  the  larynx ;  plan  of  its  interior  cavity,  represented  by  the 
lines  a  c,  b  b.  /s,  Superior  ligaments  of  the  glottis.  U,  Inferior  ligaments. 

41 


482  GLOTTIS. 

septum  fixed  abruptly  in  the  windpipe,  with  an  aperture  in  it 
of  the  figure  of  the  rima  glottidis. 

The  anterior  surface  of  the  two  arytenoid  cartilages  is  con- 
cave. This  concavity  is  occupied  in  each  by  a  glandular 
substance,  which  lies  between  the  cartilage  and  the  lining 
membrane ;  and  extends  itself  horizontally,  covered  by  the 
upper  ligament  of  the  glottis.  The  nature  of  these  bodies  is 
not  perfectly  understood ;  but  they  are  supposed  to  secrete 
mucus.* 

The  membrane  which  lines  the  cavity  of  the  glottis  being 
continued  from  the  mouth  and  throat,  resembles  the  membranes 
which  invest  those  parts.  In  some  places,  where  it  is  in  close 
contact  with  the  cartilages,  it  appears  united  with  the  perichon- 
drium,  and  acquires  more  firmness  and  density. 

The  general  motions  of  the  larynx  are  very  intelligible  to 
those  who  are  acquainted  with  the  muscles  which  are  con- 
nected with  the  thyroid  cartilage,  and  which  move  the  os  hy- 
oides.  They  take  place  particularly  in  deglutition,  and  in 
some  modifications  of  the  voice  ;  and  also  in  vomiting.f 

The  motions  of  the  particular  cartilages  on  each  other  can 
also  be  well  understood,  by  attending  to  the  origin  and  inser- 
tion of  the  various  small  muscles  connected  with  them.  The 
most  important  of  these  muscles  are  the  crico-arytenoidei  pos- 
tici  and  laterales,  the  thyreo-arytenoidei,  the  arytenoidei  obli- 
qui,  and  the  arytenoideus  transversus.  The  effects  of  their 
actions  appear  to  be  the  dilating  or  contracting  the  rima  glotti- 
dis, and  relaxing  or  extending  the  ligaments  which  form  it. 

The  arteries  of  the  larynx  are  derived  from  two  sources, 
namely,  the  superior  thyroid,  or  laryngeal  branch  of  the 
external  carotid,  and  the  thyroid  branch  of  the  subclavian. 

The  nerves  of  the  larynx  also  come  to  it  in  two  very  differ- 
ent directions  on  each  side.  It  receives  two  branches  from  the 
par  vagum  ;  one  which  leaves  that  nerve  high  up  in  the  neck, 
and  is  called  the  Superior  Laryngeal  branch ;  and  another 

*  They  constitute  the  glandulce  arytenoidea. — p. 

•j-  For  an  excellent  exposition  of  the  uses  of  the  larynx,  see  Dunglison's 
Physiology,  5th  edition. — 


VESSELS  AND  NERVES  OF    THE   LARYNX.  483 

which  proceeds  from  it  after  it  has  passed  into  the  cavity  of  the 
thorax,  and  is  called  from  its  direction  the  Recurrent. 

— According  to  M.  Blandin,  who  has  rather  recently  m#de 
some  research  upon  this  subject,  the  superior  laryngeal  nerve, 
is  distributed  chiefly  to  the  mucous  membrane  and  cryptae  of 
the  larynx  ;  it  likewise  sends  some  filaments  to  the  arytenoid 
and  crico-thyroid  muscles,  and  others  which  anastomose  with 
the  branches  of  the  recurrent.  The  recurrent  supplies  all  the 
muscles  of  the  larynx,  with  the  exception  of  the  crico-thyroid. 
There  is  still  among  anatomists  some  difference  of  opinion  in 
regard  to  the  distribution  of  these  nerves. — 

Muscles  of  the  Larynx. 

These  are  divided  into  extrinsic  and  intrinsic. 
— The  extrinsic  muscles,  which  are  attached  by  but  one  extre- 
mity to  the  larynx,  have  been  already  described.  They  consist 
of  the  sterno-hyoid,  omo-hyoid,  sterno-thyroid,  and  thyreo- 
hyoid  ;  to  which  might  indeed  be  added,  all  the  muscles  of  the 
supra-hyoid  region,  and  those  of  the  pharynx,  which  are 
attached  to  the  cricoid  and  thyroid  cartilages.  These,  when 
they  act  upon  the  organ,  move  the  entire  larynx. 
— The  intrinsic  muscles,  are  attached  by  both  extremities  to 
different  parts  of  the  larynx,  and  produce  various  movements 
in  the  different  pieces  of  which  it  is  composed.  There  are  ten, 
viz.,  five  pairs,  and  one  single  muscle  which  are  called  the 
muscles  of  the  chorda  vocales,  and  rima  glottidis.  Those 
which  exist  in  pairs  are  the  crico-thyroid,  the  crico-arytenoidei 
postici,  the  crico-arytenoidei  lateralis,  the  thyro-arytenoidei 
and  the  arytenoidei  obliqui.  The  single  muscle  is  the  aryte- 
noideus  transversus.  The  oblique  and  the  transverse  arytenoid 
muscles  consist,  but  of  a  few  thin  fibres  with  difficulty  distin- 
guished from  each  other  and  are  spoken  of  by  many  anato- 
mists, as  a  common  muscle,  called  simply  the  arytenoid. 
— There  are  three  other  minute  muscles,  which  are  called  the 
muscles  of  the  epiglottis,  viz.  the  thyro-epiglottideus,  the 
aryteno-epiglottideus  superior,  and  another  muscle  lately 
observed  by  Mr.  Hilton,  called  aryteno-epiglottideus  inferior. 


484 


MUSCLES  OF    THE  LARYNX. 


1 .   Crico-  Thyroideus, 

Arises  from  the  side  and 
forepart  of  the  cricoid  car- 
tilage, running  obliquely  up- 
wards. 

Inserted  by  two  portions: 
the  first,  into  the  lower  part  of 
the  thyroid  cartilage ;  the  se- 
cond, into  its  inferior  cornu. 

Use.  To  pull  forwards  and 
depress  the  thyroid,  or  to  ele- 
vate and  draw  backwards  the 
cricoid  cartilage. 

2.     Crico- Arytanoideus    Pos- 


Arises,  fleshy,  from  the  back 
part  of  the  cricoid  cartilage  ;  and  is 

Inserted  into  the  posterior  part  of  the  base  of  the  arytenoid 
cartilage. 

Use.  To  open  the  rima  glottidis  a  little,  and,  by  pulling  back 
the  arytenoid  cartilage,  to  stretch  the  ligament  so  as  to  make  it 
tense. 

3.    Crico- Arytanoideus  Later  alis, 

Arises,  fleshy,  from  the  cricoid  cartilage,  laterally,  where  it 
is  covered  by  part  of  the  thyroid,  and  is 

*  The  styloid  muscles  and  the  muscles  of  the  tongue.  1.  A  portion  of  the 
temporal  bone  of  the  left  side  of  the  skull,  including  the  styloid  and  mastoid 
processes,  and  the  meatus  auditorius  externus.  2,  2.  The  right  side  of  the  lower 
jaw,  divided  at  its  symphysis  ;  the  left  side  having  been  removed.  3.  The 
tongue.  4.  The  genio-hyoideus  muscle.  5.  The  genio-hyo-glossus.  6.  The 
hyo-glossus  muscle  ;  well  seen  at  the  base  of  the  tongue.  7.  Its  portion  con- 
nected with  the  os  hyoides.  8.  The  anterior  fibres  of  the  lingualis  issuing  from 
between  the  hyo-glossus  and  genio-hyo-glossus.  9.  The  stylo-glossus  muscle, 
with  a  small  portion  of  the  stylo-maxillary  ligament.  10.  The  stylo-hyoid. 
11.  The  stylo-pharyngeus  muscle.  12.  The  os  hyoides.  13.  The  thyro-hyoi- 
dean  membrane.  14.  The  thyroid  cartilage.  15.  The  thyro-hyoideus  muscle 
arising  from  the  oblique  line  on  the  thyroid  cartilage.  16.  The  cricoid  cartilage. 
17.  The  crico-thyroidean  membrane,  through  which  the  operation  of  laryngo- 
tomy  is  performed.  18.  The  trachea.  19.  The  commencement  of  the  oesopha- 
gus. 


MUSCLES  OF    THE  LARYNX. 


485 


Inserted  into  the  side  of  the  base  of  the  arytenoid  cartilage 
near  the  former. 

Use.  To  open  the  rima  glottidis,  by  pulling  the  ligaments 
from  each  other. 


Fig.  123.* 


4.   Thyreo-Arytanoideus, 

Arises  from  the  under  and  back  part  of 
the  middle  of  the  thyroid  cartilage ;  and, 
running  backwards  and  a  little  upwards, 
alo.ig  the  side  of  the  glottis,  is 

Inserted  into  the  arytenoid  cartilage, 
higher  up  and  farther  forwards  than  the 
crico-arytaenoideus  lateralis. 

Use.  To  pull  the  arytenoid  cartilage 
forwards  nearer  the  middle  of  the  thyroid, 
and  consequently  to  shorten  and  relax  the 
ligament  of  the  larynx  or  glottis  vera. 

5.  Arytanoideus  Obliquus, 

Arises  from  the  base  of  one  arytenoid  cartilage ;  and  crossing 
its  fellow,  is 

Inserted  near  the  tip  of  the  other  arytenoid  cartilage. 

Use.  When  both  act  they  pull  the  arytenoid  cartilages  towards 
each  other. 

N.  B.    One  of  these  is  very  often  wanting. 

The  single  muscle  is,  the 

Arytanoideus  Transversus, 

Arises  from  the  side  of  one  arytenoid  cartilage,  from  near  its 
articulation  with  the  cricoid  to  near  its  tip.  The  fibres  run 
straight  across,  and  are 

Inserted,  in  the  same  manner,  into  the  other  arytenoid  car- 
tilage. 

*  A  posterior  view  of  the  larynx.  1.  The  thyroid  cartilage.  2.  One  of  its 
ascending  cornua.  3.  One  of  the  descending  cornua.  4.  7.  The  cricoid  carti- 
lage. 5,  5.  The  arytenoid  cartilages.  6.  The  arytenoideus  muscle,  consisting 
of  oblique  and  transverse  fasciculi.  7.  The  crico-arytenoidei  postici  muscles. 
8.  The  epiglottis. 

41* 


486  MUSCLES  OF  THE  LARYNX. 

Use.  To  shut  the  rima  glottidis,  by  bringing  these  two  carti- 
lages, with  the  ligaments,  nearer  one  another. 

Fig.  124.*  Besides  these,  there  are  a  few  separate 
muscular  fibres  on  each  side ;  which,  from 
their  general  direction,  are  named 

1.   Thyro-Epiglottideus, 
Arises,  *by    a    few    pale    separated    fibres, 

from  the  thyroid  cartilage  :    and  is 
Inserted  into  the  epiglottis  laterally. 
Use.     To    draw    the    epiglottis    obliquely 

downwards,     or,    when     both     act,    directly 

downwards  ;  and  at  the  same  time,  it  expands 

that  soft  cartilage. 

2.  Aryt&no-Epiglottideus,  superior. 

Arises,  by  a  number  of  small  fibres,  from  the  lateral  and 
upper  part  of  the  arytenoid  cartilage  ;  and,  running  along  the 
outer  side  of  the  external  rima,  is 

Inserted  into  the  epiglottis  along  with  the  former. 

Use.  To  pull  that  side  of  the  epiglottis  towards  the  external 
rima ;  or,  when  both  act,  to  pull  it  close  upon  the  glottis.  It  is 
counteracted  by  the  elasticity  of  the  epiglottis. 

3.  Aryteno-Epiglottideus,  inferior. 

— This  muscle  may  be  exposed  by  raising  the  mucous  mem- 
brane immediately  above  the  ventricle  of  the  larynx.  It  arises 
by  a  narrow  and  fibrous  origin  from  the  arytenoid  cartilage, 
just  above  the  attachment  of  the  chorda  vocalis — and  passing 
forwards  and  a  little  upwards,  expands  over  the  upper  half  or 
two-thirds  of  the  sacculus  laryngis,  and  is  inserted  by  a  broad 
attachment  into  the  side  of  the  epiglottis.  Its  action  according 

*  A  side  view  of  the  larynx,  one  ala  of  the  thyroid  cartilage  has  been 
removed.  1.  The  remaining  ala  of  the  thyroid  cartilage.  2.  One  of  the 
arytenoid  cartilages.  3.  One  of  the  cornicula  laryngis.  4.  The  crycoid  carti- 
lage. 5.  The  crico-arytenoideus  posticus  muscle.  6.  The  crico-arytenoideus 
lateralis.  7.  The  thyro-arytenoideus.  8.  The  crico-thyroidean  membrane. 
9.  One  half  of  the  epiglottis.  10.  The  upper  part  of  the  trachea. 


THE  THYROID    GLAND.  487 

to  Mr.  Hilton,  is  to  approximate  the  epiglottis  and  arytenoid 
cartilage,  to  compress  the  subjacent  glands  which  open  into  the 
pouch  of  the  larynx,  to  diminish  the  capacity  of  that  cavity 
and  to  change  its  form. — 

The  extreme  irritability  of  the  glottis  is  unequivocally  demonstrated  by  the 
cough,  which  is  excited  when  a  drop  of  water,  or  any  other  mild  liquid,  or  a 
crumb  of  bread  enters  it.  Notwithstanding  this,  a  flexible  tube,  or  catheter, 
has  several  times  been  passed  into  the  windpipe  through  the  rima  glottidis, 
and  been  endured  by  the  patient  a  considerable  time. 

The  cough,  which  occurs  when  these  parts  are  irritated,  does  not  appear  to  arise 
exclusively  from  the  irritation  of  the  membrane  within  the  glottis;  for,  if  it 
were  so,  mucilaginous  substances,  when  swallowed  slowly,  could  not  suspend 
it.  Their  effect  in  relieving  cough  is  universally  known  ;  and  as  they  are 
only  applied  to  the  surface  exterior  to  the  glottis,  it  is  evident  that  the  irrita- 
tion of  this  surface  must  also  produce  coughing. 

Several  curious  experiments  have  been  made  to  determine  the  effect  of  dividing 
the  different  nerves  which  go  to  the  larynx ;  by  which  it  appears  that  the 
recurrent  branches  supply  parts  which  are  essentially  necessary  to  the  forma- 
tion of  the  voice ;  whilst  the  laryngeal  branches  supply  parts  which  merely 
influence  its  modulation,  or  tone.  See  Mr.  Haigton's  Essay  on  this  subject: 
Memoirs  of  the  Medical  Society  of  London,  vol.  iii. 

The  Thyroid  Gland,  (see  fig.  118,  p.  454,) 

May  be  described  here,  although  a  part  of  it  is  situated 
below  the  larynx. 

This  body  consists  of  two  lobes,  which  are  united  at  their 
lower  extremities  by  a  portion  which  extends  across  the 
anterior  part  of  the  windpipe.  Each  lobe  generally  rises 
upwards  and  backwards  from  the  second  cartilaginous  ring  of 
the  windpipe  over  the  cricoid  cartilage  and  a  portion  of  the 
thyroid.  It  lies  behind  the  sterno-hyoidei,  and  sterno-thyroidei 
muscles.  It  is  of  a  reddish-brown  color,  and  appears  to 
consist  of  a  granular  substance ;  but  its  ultimate  structure  is 
not  understood.  It  is  plentifully  supplied  with  blood,  and 
receives  two  arteries  on  each  side :  one  from  the  laryngeal 
branch*  of  the  external  carotid :  and  the  other  from  the  thyroid 
branch  of  the  subclavian. 

Notwithstanding    this   large   supply   of    blood,    there   is   no 

*  The  main  branch  from  the  external  carotid,  is  now  more  commonly  called 
superior  thyroid. — r. 


488  THE  THYROID    GLAND. 

proof  that  it  performs  any  secretion :  for  although  several 
respectable  anatomists  haVe  supposed  that  they  discovered 
excretory  ducts  passing  to  the  windpipe,  larynx,  or  tongue,  it 
is  now  generally  agreed  that  such  excretory  ducts  are  not  to  be 
found.  Several  instances,  have,  however,  occurred,  in  which 
air  has  been  forced,  by  violent  straining,  from  the  windpipe  into 
the  substance  of  this  gland. 

[There  are  two  membranous  expansions  in  the  neck  which 
should  be  noticed  in  its  dissection.  The  first,  called  Fascia 
Superficialis,  lies  immediately  beneath  the  skin,  may  be 
considered  as  a  continuation  of  the  fascia  superficialis  abdomi- 
nis,  and  is  strongly  connected  to  the  base  of  the  lower  jaw, 
being  also  spread  over  the  parotid  gland.  It  is  not  very 
distinct  in  all  subjects.  The  second  is  called  the  Fascia  Pro- 
funda  Cervicis ;  it  extends  from  the  larynx  and  thyroid  gland 
to  the  upper  part  of  the  sternum  and  first  ribs ;  the  great  ves- 
sels, &,c.  of  the  superior  mediastinum  are  placed  immediately 
below  it.] 

— The  thyroid  gland,  gets  a  thin  capsular  investment,  from  two 
layers  of  the  deep-seated  cervical  fascicf,  (fascia  profunda  cer- 
mcis)  as  seen  in  fig.  125. 

— The  same  fascia  likewise  gives  off  layers,  that  form  cellular 
investments  or  tunics  to  the  trachea,  oesophagus,  and  to  the 
blood-vessels  of  the  neck.  Other  processes  pass  off  from  it 
which  supply  sheaths  to  the  sterno-cleido  mastoid  and  other 
muscles  of  the  neck.  Between  the  sheaths  of  the  different 
muscles  of  the  neck,  dense  processes  of  cellular  tissue  are  con- 
tinued, so  as  to  give  them  all  the  appearance  of  being  formed 
as  it  were,  from  a  common  fascia.  At  the  posterior  part  of  the 
neck  they  are  thus  indirectly  connected  with  the  ligamentum 
nuchce.  Though  this  for  practical  purposes  is  not  considered 
the  best  way  for  studying  the  fascia  of  the  neck,  it  serves  to  give 
an  idea  of  the  continuity  of  the  cellular  investments,  which  is  so 
common  throughout  the  body.  The  accompanying  cut  and 
explanation  is  taken  from  Wilson. 

— The  two  lobes  of  the  thyroid  gland,  when  extended  and 
measured  from  side  to  side  are  together  about  three  inches  in 


THE  THYROID    GLAND.  489 

diameter.  The  lobes  extend  upwards  on  the  sides  of  the  larynx 
and  downwards  on  the  oesophagus,  and  lie  upon  the  inner  face 
of,  and  partly  covering  the  primitive  carotid  artery  and  internal 
jugular  vein.  That  part  of  the  gland  which  unites  the  lobes 

Fig. 


together,  and  is  stretched  across  the  trachea,  covering  the  two 
or  three  usually  and  sometimes  the  seven  upper  rings  of  the 
trachea,  is  called  the  isthmus  of  the  gland.  From  the  upper 
surface  of  the  isthmus  a  process  of  the  gland  is  usually  seen 

*  A  transverse  section  of  the  neck,  showing  the  deep  cervical  fascia  and  its 
numerous  prolongations,  forming  sheaths  for  the  different  muscles  of  the  neck, 
the  thyroid  gland — trachea,  O3sophagus  and  blood-vessels.  As  the  figure  is 
symmetrical,  the  figures  of  reference  are  placed  only  on  one  side.  I.  The 
platysma  myoides.  2.  The  trapezius.  3.  The  ligamentum  nuchae,  from  which 
the  fascia  may  be  traced  forwards  beneath  the  trapezius,  enclosing  the  other 
muscles  of  the  neck.  4.  The  point  at  which  the  fascia  divides,  to  form  a  sheath 
for  the  sterno-mastoid  muscle  (5).  6.  The  point  of  reunion  of  the  two  layers 
of  the  sterno-mastoid  sheath.  7.  The^point^of  union  of  the  deep  cervical  fascia 
of  opposite  sides  of  the  neck.  8.  Section  of  the  sterno-hyoid.  9.  Omo-hyoid 
10.  Sterno-thyroid.  11.  The  lateral  lobe  of  the  thyroid  gland.  12.  The 
trachea.  13.  The  oasophagus.  14.  The  sheath  containing  the  common  carotid 
artery,  internal  jugular  vein,  and  pneumogastric  nerve.  15.  The  longus  colli. 
The  nerve  in  front  of  the  sheath  of  this  muscle  is  the  sympathetic.  16.  The 
rectus  anticus  major.  17.  Scalenus  anticus.  18.  Scalenus  posticus.  19.  The 
splenius  capitis.  20.  Splenius  colli.  21.  Levator  anguli  scapulae.  22.  Corn- 
plexus.  23.  Trachelo-mastoid.  24.  Transversalis  colli.  25.  Cervicalis  ascen- 
dens.  26.  The  semi-spinalis  colli.  27.  The  multifidus  spinoe.  28.  A  vertical 
vertebra.  The  transverse  processes  are  seen  to  be  traversed  by  the  vertebral 
artery  and  vein. 


490  THE    PHARYNX. 

extending  upwards,  on  the  left  side  over  the  front  surface  of 
the  larynx,  to  be  attached  by  ligamentous  fibres  to  the  os 
hyoides.  A  small  muscle  called  the  levator  glandule  thyroideae, 
has  been  described  by  Duverney,  Soemmering  and  others,  run- 
ning down  from  the  os  hyoides  in  front  of  the  larynx  to  the 
upper  part  of  the  isthmus  of  the  gland.  According  to  Professor 
Homer,  its  existence  is  verv.  rare,  with  which  opinion  my  own 
more  limited  observation  coincides. 

— The  lobes  of  the  gland  are  composed  of  smaller  lobules,  and 
the  spongy  structure  of  the  latter,  is  filled  with  a  yellowish  and 
somewhat  oily  fluid.  Of  the  uses  of  this  gland  nothing  positively 
is  known.  Its  importance  in  the  system  of  the  adult  cannot 
be  great,  as  its  removal  by  extirpation,  which  has  been  many 
times  practised,  has  not  appeared  to  leave  any  functional  lesion 
in  the  economy. — 

Of  the  Pharynx. 

The  pharynx  is  a  large  muscular  bag,  which  forms  the  great 
cavity  behind  the  nose  and  mouth  that  terminates  in  the 
oesophagus. 

It  has  been  compared  to  a  funnel,  of  which  the  oesophagus 
is  the  pipe ;  but  it  differs  from  a  funnel  in  this  respect,  that  it  is 
incomplete  in  front,  at  the  part  occupied  by  the  nose  and  mouth 
and  larynx. 

It  is  connected  above,  to  the  cuneiform  process  of  the 
occipital  bone,  to  the  pterygoid  processes  of  the  sphenoidal, 
and  to  both  the  upper  and  lower  maxillary  bones.  It  is  in 
contact  with  the  cervical  vertebrae  behind ;  and,  opposite  to  the 
cricoid  cartilage,  it  terminates  in  the  oesophagus. 

If  the  pharynx  and  oesophagus  be  carefully  dissected  and 
detached  from  the  vertebrae,  preserving  the  connexion  of  the 
pharynx  with  the  head,  and  the  head  then  be  separated  from 
the  body,  by  dividing  the  articulation  of  the  atlas  and  the  os 
occipitis,  and  cutting  through  the  soft  parts  below  the  larynx, 
the  resemblance  to  a  funnel  will  be  very  obvious. 

In  this  situation,  if  an  incision  be  made  from  above  down- 
wards through  the  whole  extent  of  the  posterior  part  of  the 


STRUCTURE    OF    THE    PHARYNX.  491 

pharynx,  the  communication  of  the  nose,  mouth,  and  windpipe, 

with  this  cavity,  will  be  seen  from  behind  at  one  view. 

The  openings  into   the  nose,  or  the   posterior  nares,  appear 

uppermost.     Their  figure  is  irregularly  oval,  or  oblong  ;  they 

are  separated  from   each  other  by  a   thin   partition,  the   vomer. 

Immediately  behind,  on  the  external  side  of  each  of  these  orifices, 

is  the  Eustachian  tube.     (See  fig.  118,  p.  454.) 

The   soft    palate    will    appear    extending    from    the    lower 

boundary    of    the  posterior    nares,    obliquely    backwards    and 

downwards,  so    as  nearly  to   close  the  passage  into  the  mouth. 

The   uvula  hangs   from  it ;  and,  on  each  side  of  the  uvula,  the 

edge  of  the  palate  is  regularly  concave. 

Below    the    palate,    in    the    isthmus  of  the   fauces,   are   the 

ridges  or  half  arches,  and   the  tonsils  between  them.     The  half 

arch  which  presents  first,  in  this   view,  runs  obliquely  downward 

and  backward,  and  not  parallel  to  the  other. 

Close  to   the   root  of  the  tongue  is  the  epiglottis  erect  ;  and 

immediately  adjoining  it,  is  an  aperture  large  enough  to  admit 

the  end  of  a  middle-sized  finger.  This  aperture  is  widest  at 
the  extremity  next  to  the  epiglottis,  and  rather  narrower  at  the 
other  extremity :  it  is  the  glottis  or  opening  of  the  windpipe. 

When  the  larynx  is  elevated,  the  epiglottis  can  be  readily 
depressed  so  as  to  cover  it  completely. 

The  extremities  of  the  arytenoid  cartilages,  and  their 
appendices,  may  be  recognized  at  the  posterior  edge  of  the 
glottis.  At  a  short  distance  below  this  edge,  the  oesophagus 
begins. 

The  Pharynx  is  composed  of  the  membrane  continued  from 
the  nose  and  mouth  internally,  and  of  a  stratum  of  muscular 
fibres  externally.  The  internal  membrane  is  very  soft  and 
flexible  and  perforated  by  many  muciferous  ducts.  The 
surface  which  it  forms  is  rather  rough,  owing  to  the  mucous 
glands  which  it  covers.  It  has  a  red  color,  but  not  so  deep 
as  that  of  some  other  parts.  It  is  connected  to  the  muscular 
stratum  by  a  loose  cellular  membrane. 

The  muscular  coat  consists  of  three  different  portions,  which 
are  considered  as  so  many  distinct  muscles.  They  are  called 


492  CONSTRICTOR    MUSCLES    OF    THE    PHARYNX. 

the  superior,  middle,  and  inferior  constrictor  muscles  of  the 
pharynx. 

The  fibres  of  each  of  these  muscles  originate  on  'each  side, 
and  run  in  an  oblique  direction  to  meet  in  the  middle,  thus 
forming  the  posterior  external  surface  of  the  dissected  pharynx. 

The  fibres  of  the  upper  muscles  originate  from  the  cuneiform 
processes  of  the  occipital  bane,  from  the  pterygoid  processes  of 
the  os  sphenoides,  and  from  the  upper  and  lower  jaws,  near 
the  last  dentes  molares,  on  each  side.  They  unite  in  a  middle 
line  in  the  back  of  the  pharynx. 

The  fibres  of  the  middle  muscles  originate  principally  from 
the  lateral  parts  of  the  os  hyoides,  and  from  the  ligaments 
which  connect  that  bone  to  the  thyroid  cartilage.  The  supe- 
rior fibres  run  obliquely  upwards,  so  as  to  cover  a  part  of  the 
first  mentioned  muscle,  and  terminate  in  the  cuneiform  process 
of  the  occipital  bone ;  while  the  other  fibres  unite  with  those  of 
the  opposite  side  in  the  middle  line. 

The  fibres  of  the  lower  muscles  arise  from  the  thyroid  and 
the  cricoid  cartilages,  and  terminate  also  in  the  middle  line  : 
those  which  are  superior,  running  obliquely  upwards ;  the 
inferior,  nearly  in  a  transverse  direction. 

It  is  obvious,  from  the  origin  and  insertion  of  these  fibres, 
that  the  pharynx  must  have  the  power  of  contracting  its 
dimensions  in  every  respect ;  and,  particularly,  that  its  diameter 
may  be  lessened  at  any  place,  and  that  the  whole  may  be 
drawn  upwards. 


PART  VI. 
OF     THE    THORAX. 

BEFORE  the  thorax  is  described,  it  will  be  in  order  to  con- 
sider the 

Mamma ; 

Or  those  glandular  bodies  situated  on  the  anterior  part  of  it, 
which,  in  females,  are  destined  to  the  secretion  of  milk. 

These  glands  lie  between  the  skin  and  the  pectoral  muscles, 
and  are  attached  to  the  surfaces  of  those  muscles  by  cellular 
membrane. 

They  are  of  a  circular  form  ;  and  consist  of  a  whitish  firm 
substance,  divisible  into  small  masses  or  lobes,  which  are  com- 
posed of  smaller  portions  or  lobuli.  Between  these  glandular 
portions,  a  great  deal  of  adipose  matter  is  so  diffused,  that  it 
constitutes  a  considerable  part  of  the  bulk  of  the  mammae. 

The  gland,  however,  varies  greatly  in  thickness  in  the  same 
person  at  different  periods  of  life. 

The  mammae  become  much  enlarged  about  the  age  of  pu- 
berty. They  are  also  very  large  during  pregnancy  and  lacta- 
tion ;  but  after  the  period  of  child-bearing  they  diminish  con- 
siderably. They  are  supplied  with  blood  by  the  external  and 
internal  mammary  arteries,  the  branches  of  which  enter  them 
irregularly  in  several  different  places. 

The  veins  correspond  with  the  arteries. 

From  the  small  glandular  portions  that  compose  the  mamma, 
fine  excretory  tubes  arise,  which  unite  together  and  form  the 
great  lactiferous  ducts  of  the  gland.  These  ducts  proceed  in  a 
42 


494  MAMM2E. 

radiated    manner   from    the  circumference    to    the  centre,   and 
terminate  on  the  surface  of  the  nipple.* 

They  are  commonly  about  fifteen  in  number,  and  vary  con- 
siderably in  size :  the  largest  of  them  being  more  than  one-sixth 
of  an  inch  in  diameter.f 

Fig.  126.J 


They  can  be  very  readily  injected  by  the  orifices  of  the  nip- 
ple from  a  pipe  filled  with  mercury,  in  subjects  who  have  died 
during  lactation  or  pregnancy ;  but  they  are  very  small  in  sub- 
jects of  a  different  description. 

It  has  been  asserted  by  respectable  anatomists,  that  these 
ducts  communicate  freely  with  each  other;  but  they  do  not 
appear  to  do  so ;  each  duct  seems  to  be  connected  with  its  pro- 
per branches  only.<$> 

*  Described  in  the  10th  century,  by  Charles  Etienne,  Vesalius  and  Posthius, 
but  their  uses  were  unknown. — H. 

f  These  ducts  vary  in  number  in  different  individuals,  from  fifteen  to 
twenty. — p. 

$  Fig.  126,  is  a  vertical  section  of  the  mammary  gland  of  a  young  female 
who  died  during  lactation.  The  ducts  were  injected  with  wax,  and  two  dissected 
out  their  full  length  to  their  origin  in  the  lobules  of  the  gland.  2,  2,  Base  of 
the  nipple.  3,  3,  3,  Lactiferous  ducts  cut  off  at  the  base  of  the  nipple.  4,  4, 
The  top  of  the  ducts  exhibited  their  whole  length.  5,  5,  Sinuses  formed  by 
these  ducts  at  the  base  of  the  nipple.  6,  6,  6,  6,  Branches  of  these  ducts 
running  to  the  lobules.  7,  7,  7,  7,  7,  The  lobules  separated  from  each  other. 
8,  8,  The  orifices  of  these  ducts  on  the  top  of  the  nipple. 

§  See  Edinburgh  Medical  Commentaries,  vol.  i.  p.  31. — A  paper  by  Meckel. 


LACTIFEROUS    DUCTS.  495 

Haller  appears  to  have  entertained  the  remarkable  senti- 
ment, that  some  of  the  ducts  originate  in  the  adipose  matter 
about  the  gland,  as  well  as  in  the  glandular  substance.*  > 

The  papilla,  or  nipple,  in  which  these  ducts  terminate,  is  in 
the  centre  of  the  mamma  :  it  consists  of  a  firm  elastic  substance, 
and  is  nearly  cylindrical  in  form.  It  is  rendered  tumid  by 
irritation,  and  by  certain  emotions. 

— This  power  of  erectibility  of  the  nipple  is  due  to  the  presence 
of  some  contractile  tissue  in  its  composition  analogous  to  the 
dartus  structure  of  the  scrotum.  There  is  now  believed  to  be  no 
erectile  tissue  in  its  composition. — 

The  lactiferous  ducts  terminate  upon  its  extremity.  When 
it  is  elongated  they  can  freely  discharge  their  contents ;  but 
when  it  contracts,  this  discharge  is  impeded.  The  skin  imme- 
diately around  the  nipple  is  of  a  bright  red  color  in  virgins  of 
mature  age.  In  pregnant  women  it  is  sometimes  almost  black  ; 
and  in  women  who  have  borne  children  it  is  often  brownish. 
It  abounds  with  sebaceous  glands,  which  form  small  eminences 
on  its  surface. 

— During  gestation  these  follicles  or  glands  are  much  increased 
in  size,  so  as  to  become  in  consequence  of  this  enlargement,  one 
of  the  most  certain  signs  of  pregnancy.  During  suckling  they 
are  still  farther  enlarged,  so  as  to  appear  like  small  pimples 
projecting  from  the  skin,  and  serve  by  the  increased  secretion 
they  throw  out,  to  defend  the  nipple  and  areola,  from  the 
excoriating  action  of  the  saliva  of  the  child. — 

This  gland  exists  in  males,  although  it  is  very  small.  In 
boys,  soon  after  birth,  it  has  often  been  known  to  tumefy,  and 
become  very  painful,  in  consequence  of  the  secretion  and  accu- 
mulation of  a  whitish  fluid,  which  can  be  discharged  by  pres- 
sure. It  also  sometimes  swells  and  is  painful,  in  males  at  the 
age  of  puberty. 


*  Elementa  Physiologiae,  Tom.  7,  Pars  II.  page  7.  — In  the  adipose  matter 
about  the  gland,  the  lactiferous  tubes  (ducti  gdlactophori)  appear  to  communi- 
cate with  the  absorbent  vessels.  In  injecting  the  gland  with  mercury,  I  have 
frequently  found  the  metal  to  pass  off  from  the  ducts  along  the  absorbent 
vessels. — p. 


496  LACTIFEROUS    DUCTS. 

There  have  been  some  instances  in  which  it  has  secreted 
milk  in  adult  males ;  and  a  few  instances  also  in  which  it  has 
been  affected  with  cancer,  in  the  same  sex. 

The  mamma  is  plentifully  supplied  with  absorbent  vessels, 
which  pass  from  it  to  the  lymphatic  glands  in  the  axilla. 

Its  nerves  are  principally  derived  from  the  great  plexus 
formed  by  the  nerves  of  the,  arm. 

— The  skin  covering  the  mammary  gland,  is  exceedingly 
thin,  delicate  and  vascular,  and  that  of  the  nipple  and  areola, 
more  delicate  and  sensitive  than  any  other  portion. 
— Each  lactiferous  duct  by  its  branching  and  convolutions, 
forms  a  distinct  lobule  of  the  gland,  and  terminates  in  a  series 
of  vascular  granules*  the  ultimate  caecal  termination  of  the  ducts 
about  the  size  of  a  millet  seed,  which  are  readily  distinguished 
from  each  other  in  individuals  who  have  died  during  lactation. 
The  lobules  of  the  gland  vary  in  size,  which,  in  subjects  where 
the  subcutaneous  matter  is  not  abundant,  gives  a  feeling  of  un- 
evenness  or  roughness  to  the  gland. 
— There  are  no  valves  in  the  lactiferous  tubes. — 

*  Histoire  de  la  Generation,  par  Grimaud  de  Caux  et  Martin  Saint- Ange, 
4to.  Paris,  1837.— p. 


CAVITY    OF    THE    THORAX.  497 


CHAPTER  XV. 

OF  THE  GENERAL  CAVITY  OF  THE  THORAX. 

Of  the  Form  of  the  Cavity  of  the  Thorax. 

THE  osseous  structure  of  the  thorax  is  described  in  page 
155.  The  cavity  is  completed  by  the  intercostal  muscles,  which 
close  the  vacuities  between  the  ribs  ;  and  by  the  diaphragm, 
which  fill  up  the  whole  space  included  within  its  lower 
margin. 

If  we  except  the  apertures  of  the  diaphragm,  which  are 
completely  occupied  by  the  aorta,  the  vena  cava,  and  the  oeso- 
phagus, &c.,  the  only  outlet  of  this  cavity  is  above  :  it  is  formed 
by  the  upper  ribs,  the  first  dorsal  vertebra,  and  the  sternum. 
The  figure  of  this  aperture  is  between  that  of  the  circle  and 
the  oval ;  but  it  is  made  irregular  by  the  vertebrae,  and  by  the 
upper  edge  of  the  sternum. 

When  the  superior  extremities  and  the  muscles  appropriated 
to  them  are  removed,  the  external  figure  of  the  thorax  is  coni- 
cal ;  but  the  cavity  formed  by  it  is  considerably  influenced  by 
the  spine,  which  protrudes  into  it ;  while  the  ribs,  as  they  pro- 
ceed from  the  spine,  curve  backwards,  and  thus  increase  the 
prominency  of  the  cavity. 

The  diaphragm  has  a  great  effect  upon  the  figure  of  the 
cavity  of  the  thorax.  It  protrudes  into  it  from  below,  with  a 
convexity  of  such  form  that  it  has  been  compared  to  an  inver- 
ted bowl ;  so  that  although  it  arises  from  the  lower  margin  of 
the  thorax,  the  central  parts  of  it  are  nearly  as  high  as  the 
fourth  rib. 

The  position  of  the  diaphragm  is  also  oblique.  The  anterior 
portion  of  its  margin,  being'connected  to  the  seventh  and  eighth 
ribs,  is  much  higher  than  the  posterior  portion,  which  is.attached 
to  the  eleventh  and  twelfth. 

In  consequence  of  the  figure  and  position  of  the  diaphragm, 
42* 


498  PLEURJE. 

the  form  of  the  cavity  of  the  thorax  resembles  that  of  the  hoof 
of  the  ox  when  its  posterior  part  is  presented  forwards. 

Of  the  Arrangement  of  the  Pleura. 

The  thorax  contains  the  two  lungs  and  the  heart,  as  well  as 
several  very  important  parts  of  smaller  size. 

The  lungs  occupy  the  greatest  part  of  the  cavity ;  ana  to 
each  of  them  is  appointed  a  complete  sac,  called  Pleura,  which 
is  so  arranged  that  it  covers  the  surface  of  the  lungs,  and  is 
continued  from  it  to  the  contiguous  surface  of  the  thorax, 
which  it  lines.  After  covering  the  lung,  it  is  extended  from  it 
to  the  spine  posteriorly :  so  that  in  tracing  the  pleura  in  a 
circular  direction,  if  you  begin  at  the  sternum,  it  proceeds  on 
the  inside  of  the  ribs,  to  the  spine ;  at  the  spine  it  leaves  the 
surface  of  the  thorax,  and  proceeds  directly  forwards  towards 
the  sternum.  In  its  course  from  the  spine  to  the  sternum,  it  soon 
meets  with  the  great  branch  of  the  windpipe  and  blood-vessels, 
which  go  to  the  lung :  it  continues  on  these  vessels  and  round 
the  lung  until  it  arrives  at  the  anterior  side  of  the  vessels,  when 
it  again  proceeds  forwards  until  it  arrives  at  the  sternum.  Each 
sac  being  arranged  in  the  same  way,  there  is  a  part  of  each 
extended  from  the  spine  to  the  sternum.  These  two  laminae 
form  the  great  vertical  septum  of  the  thorax,  called  Medias- 
tinum. They  are  situated  at  some  distance  from  each  other; 
and  the  heart,  with  its  investing  membrane  or  pericardium,  is 
placed  between  them. 

The  pericardium  is  also  a  complete  sac  or  bladder,  which, 
after  covering  perfectly  the  surface  of  the  heart,  is  extended 
from  it  so  as  to  form  a  sac,  which  lies  loose  about  it,  and 
appears  to  contain  it.  This  loose  portion  adheres  to  those  parts 
of  the  laminae  of  the  mediastinum,  with  which  it  is  contiguous ; 
and  thus  three  chambers  are  formed  within  the  cavity  of  the 
thorax:  one  for  each  lung,  and  one  for  the  heart. 

The  two  laminae  of  the  pleura,  which  constitute  the  mediasti- 
num, are  at  different  distances  from  each  other,  in  different 
places.  At  the  upper  part  of  the  thorax,  they  approach  each 
other  from  the  internal  edges  of  the  first  ribs ;  and  as  these 


MEDIASTINUM.  499 

include  a  space  which  is  nearly  circular,  the  vacuity  between 
these  laminae  is  necessarily  of  that  form,  at  its  commencement 
above. 

Here,  therefore,  is  a  space  between  them  above,  (Superior 
Mediastinum)  which  is  occupied  by  the  transverse  vein  that 
carries  the  blood  of  the  left  subclavian  and  the  left  internal 
jugular  to  the  superior  cava  ;  by  the  trachea ;  by  the  oesopha- 
gus ;  and  by  the  subclavian  and  carotid  arteries,  as  they  rise 
from  the  curve  of  the  aorta.  This  space  is  bounded  below  by 
the  above  mentioned  curve  of  the  aorta. 

The  heart  and  pericardium  are  so  placed  that  there  is  a 
small  distance  between  them  and  the  sternum  :  in  this  space 
the  two  laminae  of  the  mediastinum  are  very  near  to  each 
other  ;  and  cellular  substance  intervenes  between  them.  This 
portion  of  the  mediastinum  is  called  the  Anterior  Medias- 
tinum.* 

Posteriorly,  the  heart  and  pericardium  are  also  at  a  small 
distance  from  the  spine  ;  and  here  the  lamina  of  the  mediasti- 
num are  at  a  greater  distance  from  each  other,  and  form  a 
long  narrow  cavity  which  extends  down  the  thorax  in  front  of 
the  vertebrae  :  this  is  called  the  Posterior  Mediastinum.  It 
contains  a  considerable  portion  of  the  aorta  as  it  descends  from 
its  curve,  the  oesophagus,  the  thoracic  duct,  and  the  vena  azygos. 
The  aorta  is  in  contact  with  the  left  lamen,  and  can  often  be 
seen,  through  it  when  the  left  lung  is  lifted  up. 
— The  posterior  and  anterior  mediastina  are  separated  from 
each  other  by  the  pericardium  which  encloses  the  heart.  But  as 
the  serous  layers  of  the  anterior,  are  reflected  one  on  each  side 
of  the  pericardium,  to  meet  the  posterior  mediastinum,  it 
appears  to  -me  to  render  the  study  of  this  part  more  easy,  to 


*  This  mediastinum,  being  placed  in  front  of  the  longitudinal  diameter  of 
the  pericardium  is  found  at  its  lower  part  inclined  to  the  left  of  the  middle  line. 
The  cellular  tissue  between  its  layers,  communicates  indirectly  with  the  cellular 
tissue  on  the  outer  side  of  the  peritoneum,  in  the  notch  formed  by  the  origin  of 
the  greater  muscle  of  the  diaphragm,  under  the  xiphoid  appendix  of  the 
sternum.  By  this  channel,  abscesses  of  the  anterior  mediastinum,  may  make 
their  way  externally  upon  the  abdomen. — p. 


500  PREPARATION    OF    THE    THORAX. 

• 

consider  that  embracing  the  pericardium  as  a  middle  medias- 
tinum. 

The  oesophagus  is  in  contact  with  the  right  lamen  ;  in  its 
progress  downwards,  it  inclines  to  the  left  side  and  is  advanced 
before  the  aorta. 

The  vena  azygos  appears  posterior  to  the  oesophagus  ;  it 
proceeds  upwards  until  it  is  as  high  as  the  right  branch  of  the 
windpipe  :  here  it  bends  forward,  round  that  branch,  and  opens 
into  the  superior  cava,  laefore  that  vein  opens  into  the  right 
auricle. 

The  thoracic  duct  proceeds  upwards  from  below,  lying  in  the 
space  between  the  aorta  and  the  vena  azygos,  until  the  begin- 
ning of  the  curve  of  the  aorta,  when  it  inclines  to  the  left,  pro- 
ceeding towards  the  place  of  its  termination. 

— The  anterior  and  posterior  mediastina  are  formed  as  is 
shown  above,  by  the  layers  of  the  pleura,  between  the  sternum 
and  pericardium,  and  between  the  pericardium  and  spine. 
But  the  pericardium  does  not  extend  the  whole  length  of  the 
thoracic  cavity  ;  it  terminates  about  two  inches  short  of  the  top 
of  the  sternum,  and  at  this  part,  there  being  nothing  interposed 
to  divide  the  layers  into  an  anterior  and  posterior  portion,  they 
pass  directly  from  the  vertebrae  to  the  sternum,  and  constitute 
what  is  called  the  Superior  Mediastinum.  The  two  layers  con- 
stituting this,  continuous  below  with  the  anterior  and  superior 
mediastina,  and  each  lining  the  upper  margin  of  the  first  rib,  so 
as  to  form  a  conical  pouch  projecting  a  slight  distance  above 
the  middle  of  the  clavicle,  constitute  a  triangular  cavity,  the 
base  of  which  is  upwards,  and  corresponds  to  the  root  of  the 
neck.  This  cavity  contains  the  thymus  gland,  the  arteria 
innominata,  the  primitive  carotid  and  subclavian  of  the  left  side, 
the  superior  vena  cava,  the  trachea,  oesophagus,  and  par  vagum 
nerves. 

— The  sympathetic  nerve  is  not  contained  in  this  mediastinum  ; 
it  passes  a  little  to  the  "outside  of  the  posterior  external  angle 
of  it.— 

The  formation  of  the  mediastinum,  and  the  arrangement  of  the  pleura,  as  well 
as  the  connexion  of  these  membranes  with  the  parts  contained  in  the  thorax, 


PREPARATION    OF    THE    THORAX.  501 

may  be  studied  advantageously,  after  the  subject  has  been  prepared  in  the 
manner  now  to  be  described. 

Take  away,  from  each  side,  the  five  ribs  which  are  situated  between  the  first 
and  last  true  ribs,  by  separating  their  cartilages  from  the  sternum,  alfd  their 
heads  from  the  spine  ;  so  that  the  great  cavities  of  the  thorax  majf  be  laid 
open. 

The  precise  course  of  the  mediastinum  is  thus  rendered  obvious;  and  the 
sternum  may  now  be  divided  with  a  saw  throughout  its  whole  length  in  the 
same  direction  j  so  that  the  division  of  the  bone  may  correspond  with  the 
space  between  the  lamina  of  the  mediastinum. 

Separate  the  portion  of  the  sternum  cautiously,  so  as  to  avoid  lacerating  the 
lamina  of  mediastinum ;  and  to  keep  them  separate,  while  the  trachea  is 
dissected  from  the  neck  into  the  cavity  of  the  thorax  ;  the  great  transverse 
vein  and  the  descending  cava  are  dissected  to  the  pericardium  ;  and  the  left 
carotid  artery,  with  the  right  subclavian  and  carotid,  are  dissected  to  the  curve 
of  the  aorta,  taking  care  not  to  destroy  the  lamina  of  the  mediastinum. 

After  this  preparation  the  upper  space  between  the  lamina  of  the  mediastinum 
can  be  examined,  and  the  relative  situation  of  the  trachea  and  the  great 
vessels  in  it  can  be  understood.  The  anterior  mediastinum  can  also  be 
studied  :  the  root  of  each  lung,  or  its  connexion  with  the  mediastinum,  may 
be  seen  perfectly ;  and  the  precise  situation  of  the  lung,  in  its  proper  cavity, 
may  be  well  conceived. 

After  this,  while  the  portions  of  the  sternum  are  separated,  the  pericardium 
may  be  opened,  and  the  heart  brought  into  view  :  the  attachment  of  the 
pericardium,  and  to  the  mediastinum,  and  to  the  diaphragm,  may  be  seen 
with  advantage  in  this  situation.  The  portions  of  the  sternum  may  now  be 
detached  from  the  ribs,  with  which  they  remain  connected ;  and  further  dis- 
section may  be  performed  to  examine  the  posterior  mediastinum  and  Us  con- 
tents, and  the  parts  which  constitute  the  roots  of  the  lungs. 


502  THE     PERICARDIUM. 


CHAPTER  XVI. 

- 

OF  THE  HEART  AND  PERICARDIUM,  AND  THE  GREAT  VESSELS 
CONNECTED  WITH  THE  HEART. 

Of  the  Pericardium. 

THE  heart  is  enclosed  by  a  membranous  sac,  which,  upon  a 
superficial  view,  seems  only  connected  with  its  great  vessels. 

— The  whole  of  the  organ  lays  unattached  in  the  cavity  of 
the  sac,  except,  by  the  arteries  and  veins  connected  with  its 
base.  The  sac  is  in  fact  composed  of  two  layers,  one  external 
and  fibrous,  and  one  internal  and  serous ;  the  latter  of  these  not 
only  lines  the  inner  face  of  the  outer  membrane,  but  is  reflected 
like  other  serous  membranes,  over  the  roots  of  the  vessels 
placed  in  the  pericardium,  and  over  the  whole  of  the  outer  sur- 
face of  the  heart  itself.  This  internal  serous  lining  is  very  thin 
and  delicate,  and  can  only  be  raised  in  small  shreds,  either 
rom  the  outer  layer  of  the  pericardium,  or  from  the  heart ; 
except  at  the  base  of  the  latter  organ,  where,  in  females,  it  is 
usually,  and  in  males,  frequently,  separated  from  the  muscular 
tissue,  by  some  sub-serous  fatty  matter. — 

If  it  were  dissected  from  the  heart,  without  laceration  or 
wounding,  it  would  be  an  entire  sac. 

The  pericardium,  thus  arranged,  is  placed  between  the  two 
lamina  of  the  mediastinum,  and  adheres  firmly  to  them  where 
they  are  contiguous  to  it ;  it  also  adheres  firmly  to  the  dia- 
phragm below,  and  thus  preserves  the  heart  in  its  proper 
position. 

The  figure  of  the  pericardium,  when  it  is  distended,  is  some- 
what conical ;  the  base  being  on  the  diaphragm.  The  cavity 
formed  by  it  is  larger  than  the  heart  after  death,  but  it  is 
probable,  that  the  heart  nearly  fills  it  during  life ;  for  when  this 


THE     PERICARDIUM.  503 

organ  is  distended  by  injection,  it  often  occupies  the  whole  cavity 
of  the  pericardium. 

— The  attachment  of  the  pericardium  to  the  diaphragm,  is 
exactly  over  the  cordiform  tendon  of  the  latter.  The  French 
anatomists  have  erroneously  considered  the  fibrous  layer  of  the 
pericardium,  as  a  mere  reflection  of  the  tendon  upwards.  By 
separating  them  with  a  knife,  we  find,  they  are  united  by  a 
short  cellular  tissue,  which  is  densest  and  strongest  at  the  peri- 
phery of  their  junction.  The  sides  of  the  pericardium  are 
covered  in  part  by  the  pleura,  which  gives  the  sac  the  appear- 
ance of  being  formed  by  three  tunics. 

— Underneath   the  pleural  lining,  is   found  the   phrenic   nerve, 
and  in  fat  subjects,  a  good  deal  of  adipose  matter. — 

The  pericardium  is  composed  of  two  lamina,  the  internal  of 
which  covers  the  heart,  as  has  been  already  described ;  while 
the  external  merely  extends  over  the  loose  portion  of  the  other, 
and  blends  itself  with  the  mediastinum,  where  that  membrane 
invests  the  great  vessels. 

— Its  principal  attachment  or  termination  above,  is  upon  the 
arteries  and  veins  entering  the  heart,  (with  the  exception  of  the 
vena  cava  inferior,)  over  which  it  sends  tubular  prolongations, 
which  gradually  blend  with  their  external  coats.  Between  these 
prolongations  on  the  inside  of  the  sac,  hollow  pouches  are 
necessarily  left,  which  are  called  the  cornua  of  the  pericardium. 
— The  fibrous  layer  of  the  pericardium  resembles  in  structure 
and  appearance,  the  dura  mater  of  the  brain. 
— The  arteries  of  the  pericardium  are  very  small ;  they  are  de- 
rived from  the  phrenic,  bronchial,  cesophageal,  internal  mam- 
mary arteries,  and  from  the  aorta  itself.  Its  veins  terminate  in 
the  vena  azygos.  Its  nerves  are  few  and  small,  and  originate 
from  the  cardiac  plexus. — - 

The  internal  surface  of  the  pericardium  is  very  smooth  and 
polished  ;  and  in  the  living  subject  is  constantly  moistened  with 
a  fluid  which  is  probably  effused  from  the  exhalent  vessels  on 
its  surface. 

The  quantity  of  this  fluid  does  not  commonly  exceed  two 
drachms ;  but  in  cases  of  disease  it  sometimes  amounts  to 


504  THE    HEART. 

many  ounces.*  It  is  naturally  transparent,  but  slightly  tinged 
with  red  in  children,  and  yellow  in  old  persons.  It  is  often 
slightly  tinged  with  red  in  persons  who  have  died  by  violence. 

Of  the  Heart. 

The  great  organ  of  the  circulation  consists  of  muscular 
fibres,  which  are  so  arranged  that  they  give  it  a  conical  form, 
and  compose  four  distinct  cavities  within  it. 

Two  of  these  cavities,  which  are  called  Auricles,  receive  the 
contents  of  the  veins  ;  the  other  two  communicate  with  the 
arteries,  and  are  called  Ventricles. 

The  auricles  form  the  basis  of  the  cone  ;  the  ventricles  the 
body  and  apex. 

The  structure  of  the  auricles  is  much  less  firm  than  that  of 
the  ventricles,  and  consists  of  a  smaller  proportion  of  muscular 
fibres.  They  appear  like  appendages  of  the  heart,  while  the 
ventricles  compose  the  body  of  the  viscus. 

The  ventricles  are  very  thick,  and  are  composed  of  muscular 
fibres  closely  compacted. 

The  figure  of  the  heart  is  not  regularly  conical ;  for  a  portion 
of  it,  extending  from  the  apex  to  the  base,  is  flattened  ;  and 
in  its  natural  position,  this  flat  part  of  the  surface  is  down- 
wards. 

It  is  placed  obliquely  in  the  body  ;  so  that  its  base  presents 
backward  and  to  the  right,  and  its  apex  forward  and  to  the 
left. 

Notwithstanding  this  obliquity,  the  terms  right  and  left  are 
applied  to  the  different  sides  of  the  heart,  and  to  the  different 
auricles  and  ventricles  ;  although  they  might,  with  equal  pro- 
priety, be  called  anterior  and  posterior. 

/     The  two  great    veins  called   Vena    Cavce,  which  bring  the 

blood  from  every  part  of  the  body,  open  into  the  right  auricle 

\  from  above  and  below  ;    the  right  auricle  opens  into  the  right 

*  The  pericardium  has  been  so  distended,  by  effusion  in  dropsy,  that  it  has 
formed  a  tumour,  protruding  on  the  neck  from  under  the  sternum.  This 
tumour  had  a  strong  pulsating  motion.  It  disappeared  completely  when  the 
other  hydropic  symptoms  were  relieved. 


RIGHT    AURICLE. 


505 


ventricle;    and   from    this   ventricle  arises    the  artery   denomi- 
nated Pulmonary,  which  passes  to  the  lungs. 

The  Pulmonary  veins,  which  bring  back  the  bloody  from 
the  lungs,  open  into  the  left  auricle  ;  this  auricle  opens  into  the 
left  ventricle ;  and  from  this  ventricle  proceeds  the  Aorta, 
or  great  artery,  which  carries  blood  to  every  part  of  the 
body. 

The  heart  is  preserved  in  its  position,  1st,  by  the  venae  cavae 
which  are  connected  to  all  the  parts  with  which  they  are  con- 
tiguous in  their  course ;  2d,  by  the  vessels  which  pass  between 
it  and  the  lungs,  which  are  retained  in  a  particular  position  by 
the  mediastinum ;  3d,  by  the  aorta,  which  is  attached  to  the 
mediastinum  in  its  course  downwards,  after  making  its  great 
curve ;  and  4th,  by  the  pericardium,  which  is  attached  to  the 
great  vessels  and  to  the  mediastinum.  By  these  different 
modes  the  basis  of  the  heart  is  fixed,  while  its  body  and  apex 
are  perfectly  free  from  attachment,  and  only  contiguous  to  the 
pericardium. 

The  external  surface  of  the 
heart,  being  formed  by  the  serous 
layer  of  the  pericardium,  is  very 
smooth :  under  this  surface  a 
large  quantity  of  fat  is  often 
found. 

The  two  auricles  are  contigu- 
ous to  each  other  at  the  base, 
and  are  separated  by  a  partition 
which  is  common  to  both. 

The  Right  Auricle  originates 
from    the    junction    of    the    two 
venae    cavae.      These    veins    are 
U  united  at  some  distance  behind 


Fig. 


*  Longitudinal  section  of  the  heart,  showing  its  cavities.  *,  Right  ventri- 
cle, c,  Septum  ventriculorum.  d,  Right  auricle,  e,  Left  auricle.  /,  Section 
of  the  mitral  valves,  g,  Section  of  tricuspid  valves,  h,  Arch  of  aorta.  A, 
Descending  aorta,  i,  i,  Vena  cava  superior  and  inferior,  k,  k,  Right  and  left 
branches  of  the  pulmonary  artery.  I,  I,  Pulmonary  veins. 
43 


506 


RIGHT    AURICLE. 


the  right*  ventricle,  and  are  dilated  anteriorly  into  a  sac  or 
pouch,  which  is  called  the  Sinus,  and  extends  to  the  right  ven- 
tricle, to  which  it  is  united.f 

The  upper  part  of  this  pouch,  or  sinus,  forms  a  point  with 
indented  edges,  which  is  detached  from  the  ventricle,  but  lies 
loose  on  the  right  side  of  the  aorta.  This  point  has  some 
resemblance  to  the  ear  of  a. dog,  from  which  circumstance  the 
whole  cavity  has  been  called  auricle  ;  but  by  many  persons 
the  cavity  is  considered  as  consisting  of  two  portions :  the 
Auricle,  strictly  speaking ;  and  the  Sinus  Venosus,  above 
described  :  they  however  form  but  one  cavity. 

This  portion  of  the  heart,  or  Right  Auricle,  is  of  an  irregular 
oblong  figure.  In  its  posterior  surface,  it  is  indented ;  for  the 
direction  of  the  two  cavae,  at  their  junction,  is  not  precisely  the 
same;  but  they  form  an  angle,  which  causes  this  indentation. 
The  anterior  portion  of  the  auricle,  or  that  which  appears  like 
a  pouch  between  the  ventricle  and  the  veins,  is  different  in  its 
structure  from  the  posterior  part,  which  is  strictly  a  portion  of 
the  veins.  It  consists  simply  of  muscular  fibres,  which  are 
arranged  in  fasciculi  that  cover  the  whole  internal  surface :  this 
is  also  the  case  with  the  point,  or  that  part  which  is  strictly 
called  auricle. 

These  fasciculi  are  denominated  Musculi  Pectinati,  from 
their  resemblance  to  the  teeth  of  a  comb. 

That  part  of  the  internal  surface,  which  is  formed  by  the 
septum  is  smooth,  and  the  whole  is  covered  by  a  delicate  mem- 
brane. 

On  the  surface  of  the  septum,  below  the  middle,  is  an  oval 
depression,  which  has  a  thick  edge  or  margin:  this  is  called 
the  Fossa  Ovalis.^  In  the  foetal  heart,  it  was  the  Foramen 
Ovale,  or  aperture  which  forms  the  communication  between 
the  two  auricles. 

*  In  this  description  the  heart  is  supposed  to  be  in  its  natural  position. 

•}•  At  the  place  of  junction  of  these  veins  there  is  a  projection,  indistinctly 
seen  in  man,  but  very  manifest  in  some  of  the  larger  mammalia,  called  tuber- 
culum  Loweri. — P. 

:£  The  thick  edge  or  margin  is  spoken  of  as  the  annulus  ovalis. — P. 


RIGHT    AURICLE.  507 

Near  this  fossa  is  a  large  semilunar  plait,  or  valve,  with  its 
points  and  concave  edge  uppermost,  and  convex  edge  down- 
wards. It  was  described  by  Eustachius,  and  therefore,  is 
called  the  Valve  of  Eustachius. 

— It  commences  at  the  lower  surface  of  the  opening  of  the 
inferior  vena  cava,  and  runs  forwards  to  terminate  below  the 
fossa  ovalis.  It  served  in  the  foetus  to  obstruct  the  passage 
of  the  venous  blood  from  the  right  auricle  into  the  right  ven- 
tricle, and  to  direct  it  in  a  great  measure  through  the  foramen 
ovale. — 

Anterior  to  this  valve,  and  near  the  union  of  the  auricle  and 
ventricle,  is  the  orifice  of  the  proper  vein  of  the  heart,  or  the 
coronary  vein.  This  orifice  is  covered  by  another  semilunar 
valve,  which  is  sometimes  reticulated.* 

The  aperture,  which  forms  the  communication  between  the 
right  auricle  and  right  ventricle,  is  about  an  inch  in  diameter, 
and  is  called  ostium  venosum.  From  its  whole  margin  arises 
a  valvular  ring,  or  duplicature  of  the  membrane  lining  the 
surface :  this  circular  valve  is  divided  into  three  angular  por- 
tions, which  are  called  Valvula  Tricuspides.  From  their 
margins  proceed  a  great  number  of  fine  tendinous  threads, 
which  are  connected  to  a  number  of  distinct  portions  of  mus- 
cular substance,  which  arise  from  the  ventricle. 

The  Right  Ventricle,  when  examined  separately  from  the 
other  parts  of  the  heart,  is  rather  triangular  in  its  figure,  It  is 
composed  entirely  of  muscular  fibres  closely  compacted  ;  and 
is  much  thicker  than  the  auricle,  although  not  so  thick  as  the 
other  ventricle.  Its  internal  surface  is  composed  of  bundles  or 
columns  of  fleshy  fibres,  which  are  of  various  thickness  and 
length.  Some  of  these  columns  (columna  carne<z)  arise  from 
the  ventricle,  and  are  connected  with  the  tendinous  threads, 
(chorda  tendinea?)  which  are  attached  to  the  margin  of  the 
tricuspid  valves  :  the  direction  of  them  is  from  the  apex  of  the 


*  The  orifice  is  called  the  foramen  Thebesii,  and  the  valve  valvula  Thebesii, 
from  the  anatomist  who  first  described  them. 

There  are  several  other  orifices  in  the  neighborhood  of  the  foramen  of  The- 
besius,  by  which  some  of  the  lesser  coronary  veins  discharge  into  the  right 
auricle. — p. 


508 


RIGHT    VENTRICLE. 


heart  towards  the  base.  Others  of  the  columns  arise  from  one 
part  of  the  surface  of  the  ventricle,  and  are  inserted  into  another 
part.  A  third  species  are  attached  to  the  ventricle  throughout 
their  whole  length,  forming  ridges  or  eminences  on  it.  The 
columns  of  the  two  last  described  species  are  very  numerous. 
They  present  an  elegant  reticulated  surface  when  the  ventricle 
is  laid  open,  and  appear  also  to  occupy  a  considerable  portion 
of  the  cavity  of  the  heart,  which  some  of  them  run  across  in 
every  direction  near  the  apex.  They  are  all  covered  by  a 
membrane  continued  from  the  auricle  and  the  tricuspid  valves  ; 
but  this  membrane  appears  more  delicate  and  transparent  in 
the  ventricle  than  it  is  in  the  auricle. 

— This  is  called  the  internal  serous,  or  endo-cardial  lining 
membrane  of  the  heart.  On  the  right  side  it  is  continuous  with 
that  of  the  veins  and  pulmonary  artery,  on  the  left  with  the 
aorta  and  pulmonary  veins.  It  is  extremely  thin,  smooth,  and 
transparent,  covers  all  the  interior  surface  of  the  cavities  of  the 
heart,  and  by  being  thrown  into  folds,  with  some  fibrous  matter 
interposed  between  the  layers  to  increase  their  strength,  con- 
stitutes the  valves. — 

A  portion  of  the  internal  surface  of  the  ventricle,  which  is  to 
the  left,  is  much  smoother  and  less  fasciculated  than  the  rest : 
it  leads  to  the  orifice  of  the  pulmonary  artery,  which  arises 
from  it  near  the  basis  of  the  ventricle.  This  artery  is  very 
conspicuous,  externally,  at  the  basis  of  the  heart. 

It  is  very  evident,  upon  the  first  inspection  of  the  heart,  that 
the  valvulse  tricuspides  will  permit  the  blood  to  flow  from  the 
auricle  to  the  ventricle  ;  but  must  rise  and  close  the  orifice,  and 
thereby  prevent  its  passage  back  again,  when  the  ventricle 
contracts. 

The  use  of  the  tendinous  threads,  which  connect  the  valves 
to  the  fleshy  columns,  is  also  very  evident ;  the  valve  is  sup- 
ported by  this  connexion,  and  prevented  from  yielding  to  the 
pressure  and  opening  a  passage  into  the  auricle.  The  blood, 
therefore,  upon  the  contraction  of  the  ventricle,  is  necessarily 
forced  into  the  pulmonary  artery  ;  the  passage  to  which  is  now 
perfectly  free.  In  this  artery  the  membrane  lining  the  ventricle 


LEFT     AURICLE.  509 

seems  continued ;  but  immediately  within  the  orifice  of  the 
artery,  it  is  formed  into  three  semicircular  folds,  each  of  which 
adheres  to  the  surface  of  the  artery  by  its  circumference,  while 
the  edge  constituting  its  diameter  is  loose.  In  the  middle  of 
this  loose  edge  is  a  small  firm  tubercle,  called  Corpusculum 
Arantii*  which  adds  to  the  strength  of  the  valve.  Each  of 
these  valves,  by  its  connexion  with  the  artery,  forms  a  sac  or 
pocket,  the  orifice  of  which  opens  forward  towards  the  course 
of  the  artery,  and  the  bottom  of  it  presents  towards  the  ventricle. 
Blood  will,  therefore,  pass  from  the  ventricle  in  the  artery,  and 
along  it  without  filling  these  sacs ;  and,  on  the  contrary,  in  this 
course,  will  compress  them  and  keep  them  empty.  If  it  moves 
in  the  artery  towards  the  heart,  it  will  necessarily  fill  these 
sacs,  and  press  the  semicircular  portions,  from  the  sides  of  the 
artery,  against  each  other ;  by  this  means  a  partition  or  septum, 
consisting  of  three  portions,  will,  be  formed  between  the 
artery  and  the  heart,  which  will  always  exist  when  the 
artery  compresses,  (or  acts  upon,)  its  contents.  It  is  demon- 
strable, by  injecting  wax  into  the  artery,  in  a  retrogade 
direction,  that  these  valves  do  not  form  a  flat  septum,  but  one 
which  is  convex  towards  the  heart,  and  concave  towards  the 
artery ;  and  that  this  convexity  is  composed  of  three  distinct 
parts,  each  of  which  is  convex.  At  the  place  where  these 
valves  are  fixed,  the  artery  bulges  out  when  extended  by  a 
retrogade  injection.  The  enlargements  thus  produced  are 
called  the  Sinuses  of  Valsalva,  after  the  anatomist  who  first 
described  them.  The  valves  are  called  Semilunar — and, 
although  they  are  formed  by  a  very  thin  membrane,  they  are 
very  strong. 

The  Left  Auricle  is  situated  on  the  left  side  of  the  basis  of 
the  heart.  It  originates  from  the  junction  of  the  four  pulmo- 
nary veins  ;  two  of  which  come  from  each  side  of  the  thorax, 
and  appear  to  form  a  large  part  of  it.  It  is  nearly  of  a  cubic 
form:  but  has  also  an  angular  portion,  which  constitutes  the 
proper  auricle,  that  proceeds  from  the  upper  and  left  part  of 

*  After  Arantius,  a  professor  at  Bologna,  who  first  described  it. 
43* 


510  LEFT    VENTRICLE. 

the  cavity,  and  is  situated  on  the  left  side  of  the  pulmonary 
artery. 

This  auricle  is  lined  by  a  small  membrane,  from  which  the 
valves  between  it  and  the  ventricle  originate  ;  but  it  has  no 
fleshy  columns  or  musculi  pectinati,  except  in  the  angular  pro- 
cess properly  called  auricle. 

These  valves  and  the  ^orifice  communicating  with  the 
ventricle,  resemble  those  which  have  been  already  described 
between  the  right  auricle  and  ventricle :  but  with  this  differ- 
ence, that  the  valvular  ring  is  divided  into  two  portions  only, 
instead  of  three  which  are  called  Valvula  Mitrales.*  The 
tendinous  threads,  which  are  connected  to  the  muscular 
columns,  are  also  attached  to  these  valves,  as  in  the  case  of  the 
right  auricle. 

These  valves  admit  the  passage  of  blood  from  the  auricle  into 
the  ventricle,  but  completely  prevent  its  return  when  the 
ventricle  contracts.  One  of  them  is  so  situated  that  it  covers 
the  mouth  of  the  aorta  while  the  blood  is  flowing  into  the  ven- 
tricle, and  leaves  that  orifice  open  when  the  ventricle  contracts, 
and  the  passage  to  the  auricle  is  closed. 

The  Left  Ventricle  is  situated  posteriorly,  and  to  the  left  of 
the  Right  Ventricle.  Its  figure  is  different,  for  it  is  rather  coni- 
cal, and  it  is  also  longer. 

The  internal  surface  of  this  ventricle  resembles  that  of  the 
right  ventricle :  but  the  columnae  carneae  are  stronger  and 
larger. 

On  the  right  side  of  this  ventricle  is  the  mouth  of  the  aorta. 
The  surface  of  the  ventricle  near  this  opening  is  smooth  and 
polished,  to  facilitate  the  passage  of  the  blood. 

The  mouth  of  the  aorta  is  furnished  with  three  semilunar 
valves,  after  the  manner  of  the  pulmonary  artery,  but  the 
former  are  stronger ;  the  corpuscula  Arantii  are  better  developed 
in  them.  Indeed,  Mr.  Hunter  does  not  admit  of  their  existence 
in  the  pulmonary  artery.  The  sinuses  of  Valsalva  are  about  the 
same  size  m  both  arteries. 

*  From  a  resemblance  in  shape  to  the  mitre  or  bishop's  cap. — P. 


FIBRES  OF   THE  HEART.  511 

The  cavity  of  this  ventricle  is  supposed  to  be  smaller  than 
that  of  the  right :  but  the  amount  of  the  difference  has  not  been 
accurately  ascertained.  j 

This  ventricle  must  have  much  more  force  than  the  right,  as 
its  parietes  are  so  much  thicker.  Their  thickness  often  exceeds 
half  an  inch. 

The  difference  in  the  strength  of  the  two  ventricles  probably 
corresponds  with  the  difference  between  the  extent  of  the  pul- 
monary artery  and  the  aorta. 

The  thickness  of  the  septum  between  the  ventricles  is  thicker 
than  the  sides  of  the  parietes  of  the  right  ventricle,  and  less 
thick  than  those  of  the  left. 

The  muscular  fibres  of  the  heart  are  generally  less  florid 
than  those  of  the  voluntary  muscles ;  they  are  also  more 
closely  compacted  together.  The  direction  of  many  of  them  is 
oblique  or  spiral ;  but  this  general  arrangement  is  very  intricate : 
it  is  such,  however,  that  the  cavities  of  the  heart  are  lessened, 
and  probably  completely  obliterated,  by  the  contraction  of 
these  fibres.* 

— The  muscular  fibres  of  the  heart  have  been  carefully  stu- 
died by  Wolf  and  Malpighi,  and  more  recently  still,  by  Mr. 
Searlef  and  M.  Gerdy.J  According  to  this  latter  anatomist, 
there  is  a  fibrous  zone  or  girdle  formed  around  each  auricle 
and  arterial  orifice  of  the  heart,  which  zones  are  connected 
with  each  other  and  with  the  valves.  From  these  zones  origi- 
nate all  the  muscular  fibres  of  the  heart.  Some  which  run 
upwards  and  turn  in  every  direction  round  the  auricles,  and 
form  loops,  the  extremities  of  which  are  inserted  on  the  oppo- 
site sides  of  the  zone.  Others  which  run  downwards  and  em- 
brace the  ventricles,  are  also  inserted  on  the  opposite  sides 
of  the  same  zone,  or  that  which  surrounds  the  orifices  of  the 
aorta  or  pulmonary  artery.  The  structure  of  the  ventricular 


*  Mr.  Home  has  given  a  precise  description  of  the  muscular  fibres  of  the 
heart  in  his  Croonian  Lecture.  London  Philosophical  Transactions  for  1795, 
part  I.  page  215. 

f  Cyclopedia  of  Anntomy  and  Physiology.  London. — Article — Fibres  of 
the  heart,  of  which  he  has  given  a  minute  and  lengthened  description. 

\  Journal  Complementaire  du  Diet,  des  Scienc.  Med.  torn.  ix.  p.  97. — 


512  CORONARY    VESSELS. 

fibres  is  most  complicated.  They  are  first  superficially  placed, 
and  as  they  make  their  spiral  turns,  sink  deep  into  the  sub- 
stance of  the  heart,  somewhat  like  the  contours  of  a  leaf  of 
paper  rolled  into  the  form  of  a  cone.  They  consist  of  fibres 
proper  to  each  ventricle,  and  fibres  common  to  both.  The 
former,  after  arising  from  the  zone,  turn  spirally  around  the 
axis  of  the  ventricle,  so  as  to  form  many  times  the  figure  of  8, 
and  coming  upon  the  anterior  face  of  the  same  side,  terminate 
upon  the  zone  surrounding  the  arterial  orifice.  The  fibres 
common  to  the  ventricles  are  of  two  kinds — superficial  and 
deep-seated.  The  superficial  are  divided  into  anterior  and 
posterior.  The  anterior  arising  from  the  anterior  part  of  the  arte- 
rial and  auricular  zones,  run  obliquely  downwards  and  to  the 
left,  converging  towards  the  apex  of  the  heart ;  these  are  rolled 
around  the  axis  of  the  left  ventricle,  and  dip  inwards  to  termi- 
nate in,  or  form  the  columnae  carnese.  The  superficial  part  of 
this  order  of  fibres,  is  common  to  both  ventricles  ;  the  deep- 
seated  part  belongs  to  the  left  only.  The  posterior  superficial 
fibres  arise  behind  from  the  auricular  zones  only,  and  run 
downwards,  so  as  to  embrace  the  right  border  of  the  heart, 
come  in  front  of  the  heart  and  opposite  to  the  septum  ventri- 
culorum,  dip  under  the  anterior  superficial  fibres,  wind  round 
the  axis  of  the  right  ventricle  and  terminate  in  its  columnae 
carnese.  These  also  in  part  only,  are  common  to  both  ven 
tricles. 

— The  deep-seated  fibres  form  the  internal  part  of  the  walls  of 
the  right  ventricle.  They  arise  from  the  fibrous  zones  of  the 
right  side.  The  anterior  portion  of  these  fibres  runs  obliquely 
downwards,  and  backwards  to  the  septum ;  the  posterior  and 
internal,  pass  at  once  into  the  septum,  roll  themselves  round  the 
left  ventricle  and  are  lost  amidst  the  other  fibres.  Thus  it 
appears,  that  by  removing  the  superficial  layer  of  the  common 
stratum,  the  heart  may  be  divided  into  lateral  halves,  each  con- 
sisting of  two  muscular  sacs,  an  auricle  and  ventricle,  adjoined 
to  those  of  the  opposite  side  in  the  middle  line. — 

The  external  surface  of  the  heart  is  covered  by  that  portion 
of  the  pericardium  which  adheres  to  it.     Adipose  matter  is  often 


VESSELS  AND    NERVES  OF    THE    HEART.  513 

deposited  between  this  membrane  and  the  muscular  surface; 
being  distributed  irregularly  in  various  places. 

This  membrane  is  continued  from  the  surface  of  the  ventricles 
over  that  of  the  auricles.  When  it  is  dissected  off  from  the 
place  of  their  junction,  these  surfaces  appear  very  distinct  from 
each  other. 

The  proper  blood-vessels  of  the  heart  appear  to  be  arranged 
in  conformity  to  the  general  laws  of  the  circulation,  and  are 
very  conspicuous  on  the  surface.  There  are  two  arteries 
which  arise  from  the  aorta  immediately  after  it  leaves  the  heart, 
so  that  their  orifices  are  covered  by  two  of  the  semilunar 
valves.  One  of  these  passes  from  the  aorta  between  the  pulmo- 
nary artery  and  the  right  auricle,  and  continues  in  a  circular 
course  in  the  groove  between  the  right  auricle  and  the  right 
ventricle,  and  sends  off  its  principal  branches  to  the  right  side 
of  the  heart. 

The  other  artery  of  the  heart  passes  between  the  pulmonary 
artery  and  the  left  auricle.  It  divides  into  two  branches ;  one, 
which  is  anterior,  passes  to  a  groove  on  the  surface,  corres- 
ponding to  the  septum  between  the  two  ventricles,  and  con- 
tinues on  it  to  the  apex  of  the  heart,  sending  off  branches  in 
its  course ;  another,  which  is  posterior  and  circumflex,  passes 
between  the  left  auricle  and  ventricle. 

The  great  vein  of  the  heart  opens  into  the  under  side  of  the 
right  auricle,  as  has  been  already  mentioned  :  the  main  trunk 
of  this  vein  passes  for  some  distance  between  the  left  auricle 
and  ventricle.* 


*  It  was  asserted  by  Vicussens,  at  an  early  period  in  the  last  century,  and 
soon  afterwards  by  Thebesius,  a  German  Professor,  that  there  were  a  number 
of  small  orifices  in  the  texture  of  the  heart,  which  opened  into  the  different 
cavities  on  both  sides  of  it. 

This  assertion  of  a  fact  so  difficult  to  reconcile  with  the  general  principles  of 
the  circulation,  was  received  with  great  hesitation  :  and  although  it  was  con- 
firmed by  some  very  respectable  anatomists  of  the  last  century,  it  was  denied 
by  others.  Some  of  the  anatomists  of  the  present  day  have  denied  the  existence 
of  these  orifices,  and  some  others  have  neglected  them  entirely. 

The  subject  was  brought  forward  in  the  London  Philosophical  Transactions 
of  1798,  Part  I.  by  a  very  respectable  anatomist,  Mr.  Abernethy,  who  states 
that  he  has  often  passed  a  coarse  waxen  injection  from  the  proper  arteries  and 


514  GREAT  VESSELS  OF    THE  HEART. 

From  the  course  of  these  different  vessels  round  the  basis  of 
the  ventricles  of  the  heart,  they  are  generally  called  Coronary 
Vessels :  the  arteries  are  denominated,  from  their  position,  Right 
and  Left  Coronary. 

The  nerves  of  the  heart  come  from  the  cardiac  plexus,  which 
is  composed  of  threads  derived  from  the  intercostal  or  great 
sympathetic  nerves,  and  the  nerves  of  the  eighth  pair. 

Of  the  Aorta,  the  Pulmonary  Artery  and  Veins,  and  the 
Venae,  Cava ;  at  their  commencement. 

The  two  great  arteries,  which  arise  from  the  heart,  commence 
abruptly,  and  appear  to  be  extremely  different  in  their  composi- 
tion and  structue  from  the  heart. 

They  are  composed  of  a  substance,  which  has  a  whitish 
color,  and  very  dense  texture,  and  is  very  elastic  as  well  as 
firm  and  strong. 

When  the  pericardium  is  removed,  these  arteries  appear  to 
proceed  together  from  the  upper  part  of  the  basis  of  the  heart : 
the  pulmonary  artery  being  placed  to  the  left  of  the  aorta  with 
the  left  auricle  on  the  left  side  of  it,  and  the  right  auricle  on 
the  right  side  of  the  aorta.  The  pulmonary  artery  arises  from 
the  most  anterior  and  left  part  of  the  basis  of  the  right  ven- 
tricle, and  proceeds  obliquely  backwards  and  upwards ; 
inclining  gradually  to  the  left  side  for  about  eighteen  or 
twenty  lines ;  when  it  divides  into  two  branches  which  pass  to 
the  two  lungs. 

The  aorta  arises  from  the  left  ventricle,  under  the  origin  of 

veins  of  the  heart  into  all  the  cavities  of  that  organ,  and  particularly  into  the 
Left  Ventricle.  But  it  mas  only  in  subjects  with  diseased  lungs  that  this  was 
practicable. 

The  existence  of  this  communication  between  the  coronary  vessels  and  the 
great  cavities  of  the  heart  seems  therefore  to  be  proved.  The  easy  demonstra- 
tion of  such  subjects  is  ingeniously  referred  by  Mr.  Abernethy,  to  the  obstruc- 
tion of  the  circulation  in  the  lungs ;  and  he  regards  the  communication  as  a 
provision  enabling  the  coronary  vessels  to  unload  themselves,  when  the  coronary 
vein  cannot  discharge  freely  into  the  right*  auricle.* 

*  This  assertion  of  Mr.  Abernethy 's,  has  not  been  confirmed  by  subsequent  investigations, 
except  incases  where  the  tissue  of  the  heart  was  softened,  and  its  vessels  had  been  ruptured 
by  the  force  of  the  injection,  p. 


GREAT  VESSELS   OF    THE  HEART.  515 

the  pulmonary  artery,  and  immediately  proceeds  to  the  right, 
covered  by  that  vessel,  until  it  mounts  up  between  it  and  the 
right  auricle  :  it  then  forms  a  great  curve,  or  arch,  which/ turns 
backward  and  to  the  left,  to  a  considerable  distance  beyond  the 
pulmonary  artery.  In  this  course,  it  crosses  the  right  branch  of 
the  pulmonary  artery  ;  and,  turning  down  in  the  angle  between 
it  and  the  left  branch,  takes  a  position  on  the  left  side  of  the 
spine. 

Fig.  128.* 


The  course  of  this  artery,  from  its  commencement  at  the  ven- 
tricle, to  the  end  of  the  great  curve  or  arch,  is  extremely  varied. 
The  uppermost  part  of  the  curve  is  in  the  bottom  of  the 

*  a,  Left  ventricle,  b,  Right  ventricle,  c,  Right  auricle.  The  left  auricle 
is  seen  above  the  left  ventricle  of  the  same  side,  d,  Vena  cava  inferior,  e, 
Subclavian  and  jugular  veins  j  those  of  the  left  side  unite  to  form  the  vena 
transversa ;  those  of  the  right,  to  form  the  vena  innominata  ;  the  junction  of 
these  larger  trunks,  constitutes  the  vena  cava  superior  or  descendens.  /,  Left 
carotid,  g,  Left  subclavian  artery,  arising  from  the  arch  of  the  aorta,  h,  De- 
scending aorta,  z,  k,  Right  subclavian,  and  right  carotid,  given  off  from  the 
arteria  innominata,  which  is  seen  arising  from  the  arch  of  the  aorta.  I,  Pul- 
monary artery,  dividing  into  two  branches,  one  for  each  lung — the  left  passing 
in  front  of  the  descending  aorta,  the  right,  behind  the  aorta,  where  it  begins  to 
form  the  curve,  m,  Vena  cava  superior,  n,  Aorta,  o,  Left  pulmonary  veins, 
entering  auricle  of  same  side.  The  right  pulmonary  veins,  are  seen  on  the 
opposite  side,  p,  p,  Lungs,  t,  Trachea. — p. 


516  VEN^E     CAVJE. 

chamber  formed  by  the  separation  of  the  lamina  of  the  medias- 
tinum when  they  join  the  first  rib  on  each  side. 

From  this  part  of  the  curve  three  large  branches  go  off, 
namely,  one,  which  soon  divides  into  the  carotid  and  the  sub- 
clavian  arteries  of  the  right  side ;  a  second,  somewhat  smaller, 
which  is  the  left  carotid  ;  and  a  third,  which  is  the  left  subclavian 
artery. 

When  the  heart  and  its  great  vessels  are  viewed  from  be- 
hind, (after  they  have  all  been  filled  with  injection  ;  and  the 
pericardium,  mediastinum,  and  windpipe  have  been  removed,) 
the  aorta  appears  first,  descending  behind  the  other  vessels ;  the 
pulmonary  artery  then  appears,  dividing  so  as  to  form  an  obtuse 
angle  with  its  two  great  branches,  each  of  which  divides  again 
before  it  enters  the  lung  to  which  it  is  destined. 

Under  the  main  trunk  of  the  pulmonary  artery  is  the  left 
auricle  :  its  posterior  surface  is  nearly  of  a  square  form,  and 
each  of  the  pulmonary  veins  proceeds  from  one  of  its  angles. 
These  veins  ramify  in  the  substance  of  the  lungs,  at  a  very 
short  distance  from  the  auricle  :  the  two  uppermost  of  them  are 
situated  rather  anterior  to  the  branches  of  the  pulmonary 
artery. 

In  this  posterior  view,  the  pulmonary  vessels  of  the  right  side 
cover  a  great  part  of  the  right  auricle,  as  it  is  anterior  to  them. 
The  lower  portion  of  the  auricle,  with  the  termination  of  the 
inferior  cava,  is  to  be  seen  below  them.  Above  them  the  supe- 
rior cava  appears  ;  and  in  that  part  of  it  which  is  immediately 
above  the  right  branch  of  the  pulmonary  artery,  is  the  orifice  of 
the  vena  azygos. 

In  its  natural  situation  in  the  thorax,  the  superior  cava  is 
connected  by  cellular  membrane  to  the  right  lamen  of  the 
mediastinum,  and  is  supported  by  it.  At  a  small  distance 
below  the  upper  edge  of  the  sternum,  it  receives  the  trunk 
formed  by  the  left  subclavian  and  internal  jugular  vein,  which 
passes  obliquely  across  the  sternum  below  its  inner  edge,  in  the 
upper  space  between  the  lamina  of  the  mediastinum. 


THE     TRACHEA.  517 


CHAPTER  XVII. 

OF  THE  TRACHEA  AND  THE  LUNGS. 

ALTHOUGH  the  principal  part  of  the  windpipe  is  situated  in 
the  neck  above  the  cavity  of  the  thorax,  it  is  so  intimately 
connected  with  the  lungs,  that  it  is  necessary  to  describe  them 
together. 

Of  the  Trachea. 

Trachea  is  the  technical  name  for  the  windpipe,  or  the  tube 
which  passes  from  the  larynx  to  the  lungs. 

This  tube  begins  at  the  lower  edge  of  the  cricoid  cartilage, 
and  passes  down  the  neck  in  front  of  the  oesophagus  as  low  as 
the  third  dorsal  vertebrae,  when  it  divides  into  two  branches 
called  Bronchia,  one  of  which  goes  to  the  right  and  the  other 
to  the  left  lung,  in  which  they  ramify  very  minutely. 

— The  right  bronchium  is  larger  than  the  left,  in  proportion 
to  the  greater  size  of  the  right  lung.  It  is  also  shorter  and  is 
placed  more  in  front,  and  is  more  horizontal  than  the  left,  in 
consequence  of  the  right  lung  being  shorter  in  its  vertical 
diameter,  and  longer  in  its  antero-posterior  than  the  lung  of 
the  left  side.  It  enters  near  the  centre  of  the  root  of  the  lung, 
opposite  to  the  fourth  dorsal  vertebra. 

— The  left  bronchium  enters  the  root  of  the  left  lung,  opposite 
the  fifth  dorsal  vertebrae.  The  right  bronchium  is  embraced 
at  its  upper  part  by  the  vena  azygos,  the  left  by  the  arch  of 
the  aorta. — 

There  is  in  the  structure  of  the  trachea,  a  number  of  flat  cartil- 
aginous rings  placed  at  small  distances  from  each  other,  the  edges  of 
which  are  connected  by  membrane,  so  that  they  compose  a  tube. 

These  cartilaginous  rings  are  not  complete,  for  they  do  not 
form  more  than  three-fourths  or  four-fifths  of  a  circle ;  but  their 
ends  are  connected  by  a  membrane  which  forms  the  posterior 
part  of  the  tube. 

44 


518  STRUCTURE  OF    THE  TRACHEA   AND    BRONCHIA, 

They  are  not  alike  in  their  size  or  form ;  some  of  them  are 
rendered  broader  than  others,  by  the  union  of  two  or  three 
rings  with  each  other,  as  the  uppermost.  The  lowermost  also  b 
broad,  and  has  a  form  which  is  accommodated  to  the  bifurca- 
tion of  the  tube  where  it  forms  the  bronchia.  Their  number 
varies  in  different  persons,  from  fifteen  to  twenty. 

These  rings  may  be  considered  as  forming  a  part  of  the  first 
proper  coat  of  the  trachea,  which  is  composed  of  them,  and  of 
an  elastic  membrane  that  occupies  all  the  interstice  between 
them  ;  so  that  the  cartilages  may  be  regarded  as  fixed  in  this 
membrane. 

A  similar  arrangement  of  rings  exists  in  the  great  branches 
of  the  bronchia ;  but  after  they  ramify  in  the  lungs,  the  carti- 
lages are  no  longer  in  the  form  of  rings  :  they  are  irregular  in 
their  figures,  and  are  so  arranged  in  the  membrane,  that  they 
keep  the  tube  completely  open.  These  portions  of  cartilage  do 
not  continue  throughout  the  whole  extent  of  the  ramifications ; 
for  they  become  smaller,  and  finally  disappear,  while  the  mem- 
branous tube  continues  without  them,  ramifying  minutely,  and 
probably  forming  the  air-cells  of  the  lungs. 
— At  the  orifices  of  the  bronchial  ramifications,  the  existence 
of  a  semilunar  cartilage  has  been  pointed  out  by  Prof.  Horner, 
forming  rather  more  than  half  of  their  circumference,  and 
having  its  concave  edge  turned  upwards.  These  cartilages 
appear  to  be  intended  to  keep  the  orifices  open.* — 

The  small  bronchial  tubes  after  they  become  entirely  membra- 
nous are  very  elastic  :  the  lungs  are  very  elastic  also  ;  and  it  is  pro- 
bable that  their  elasticity  is  derived  from  the  membranous  bronchiae. 

On  the  inside  of  this  coat  of  the  trachea  is  an  arrangement 
of  muscular  fibres,  which  may  be  called  a  muscular  coat.  It  is 
best  seen  by  pealing  off  or  removing  the  internal  coat,  to  be 
next  described. 

On  the  membranous  part  of  the  trachea,  where  the  cartilagi- 
rous  rings  are  deficient,  these  muscular  fibres  run  evidently  in 
r.  transverse  direction :  in  the  spaces  between  the  cartilages 


*  Special  Anatomy,  by  W.  E.  Horner,  M.  D.  Prof.  Anat.  Univers.  Penn- 
sylvania. 


STRUCTURE  OF  THE  TRACHEA.  AND  BRONCHIA.     519 

their  direction  is  longitudinal.  There  is  some  reason  to  doubt 
whether  these  longitudinal  fibres  are  confined  altogether  to 
the  spaces  between  the  cartilaginous  rings,  and  attache^  only 
to  their  edges,  because  there  is  a  fleshy  substance  on  the  inter- 
nal surface  of  the  rings,  which  appears  to  be  continued  from 
the  spaces  between  them. 

The  internal  coat  of  the  trachea  is  a  thin  and  delicate  mem- 
Fig.  129.*  brane,    perforated    with     an    im- 

mense number  of  small  foramina, 
which  are  the  orifices  of  mucous 
ducts. 

On  the  surface  of  this  mem- 
brane there  is  an  appearance  of 
longitudinal  fibres  which  are  not 
distributed  uniformly  over  it,  but 
,c  run  in  fasciculi  in  some  places, 
and  appear  to  be  deficient  in 
others.  These  fasciculi  are  par- 
ticularly conspicuous  in  the  rami- 
fications of  the  bronchia  in  the 
lungs. 

— TMany  of  the  German  anato- 
mists have  described  these  as 
longitudinal  muscular  fibres,  the 
object  of  which  is  to  shorten  to  some  extent  the  air-passages 
during  their  contraction,  and  to  assist  in  loosening  the  mucus 
and  other  matters  which  accumulate  in  their  cavities.  I  have 
examined  them  carefully  in  the  ox  and  elephant,  where 
they  are  strongly  marked ;  they  appeared  to  me  to  consist 
only  of  longitudinal  folds  of  mucous  membrane,  with  a  basis 
of  the  fibrous  contractile  tissue.  The  same  arrangement  of 
the  circular  fibres,  and  these  peculiar  longitudinal  fibres,  can 
be  traced  with  the  microscope  down  the  bronchia  as  far  as 

*  Fig.  129,  represents  the  larynx,  trachea,  and  bronchia ;  on  one  side  is  seen 
the  right  lung ;  on  the  left,  the  lung  has  been  destroyed  to  show  the  ramification 
of  the  bronchia,  a,  Larynx,  b,  Trachea,  dividing  into  right  and  left  bron- 
chium  ;  the  left  is  the  smaller,  longer,  and  inclined  most  downwards,  c,  Larger 
divisions  of  the  left  bronchium  ;  e,  the  more  minute,  d,  Right  lung. — F. 


520  THE    LUNGS. 

these  can  be  distinctly  opened.  The  contractibility  of  the  pul- 
monary tissue  under  the  influence  of  galvanism  observed  by 
Dr.  C.  J.  B.  Williams,  seems  to  establish  the  muscularity  of  the 
circular  fibres. — 

On  the  posterior  membranous  portion  of  the  trachea,  where 
the  cartilages  are  deficient,  a  considerable  number  of  small 
glandular  bodies  are  placed,  which  are  supposed  to  communicate 
with  the  mucous  ducts  that  open  on  the  internal  surface.  If 
these  bodies  are  removed  from  the  external  surface  of  this 
portion,  and  the  muscular  fibres  are  also  removed  from  the 
internal,  a  very  thin  membrane  only  remains,  which  is  very 
different  from  that  which  is  left  between  the  rings,  when  the 
fleshy  substance  is  removed  from  that  situation. 

The  reason  of  the  deficiency  in  the  rings,  at  this  posterior 
part,  is  not  very  obvious.*  It  continues  in  the  bronchia  until 
the  form  of  their  cartilages  is  changed  in  the  lungs :  if  it  were 
only  to  accommodate  the  oesophagus,  during  the  passage  of 
food,  there  would  be  no  occasion  for  its  extension  to  the 
bronchia. 

At  the  bifurcation  of  the  trachea,  and  on  the  bronchia,  are  a 
number  of  black  colored  bodies,  which  resemble  the  lymphatic 
glands  in  form  and  texture.  They  continue  on  the  ramifications 
of  the  bronchia  some  distance  into  the  substance  of  the  lungs. 
Their  number  is  often  very  considerable ;  and  they  vary  in  size 
from  three  or  four  lines  in  diameter  to  eighteen  or  twenty.  As 
lymphatic  vessels  have  been  traced  to  and  from  them  during 
their  course  to  the  thoracic  duct,  they  are  considered  as  lym- 
phatic glands. 

Of  the  Lungs. 

There  are  two  of  these  organs :  each  of  which  occupies  one 
of  the  great  cavities  of  the  thorax. 

When  placed  together,  in  their  natural  position,  they  resem- 
ble the  hoof  of  the  ox,  with  its  back  part  forward  ;  but  they  are 

*  Dr.  Physick  has  advanced  the  opinion  that  it  enables  a  person  to  expel  the 
mucus  of  the  lungs  by  contracting  the  size  of  the  trachea,  and  consequently 
increasing  the  velocity  or  impetus  of  the  air. — H. 


ROOT    OF    THE    LUNGS.  521 

at  such  a  distance  from  each  other,  and  of  such  a  figure,  that 
they  allow  the  mediastinum  and  heart  to  intervene  ;  and  they 
cover  every  part  of  the  heart  anteriorly,  except  a  small  portion 
at  the  apex. 

Each  lung  fills  completely  the  cavity  in  which  it  is  placed, 
and  every  part  of  its  external  surface  is  in  contact  with  some 
part  of  the  internal  surface  of  the  cavity  ;  but  when  in  a  natural 
and  healthy  state,  it  is  not  connected  with  any  part  except  the 
lamina  of  the  mediastinum. 

— The  lower  extremity  or  base  of  each  lung,  rests  upon  the 
pleural  lining  of  the  diaphragm,  and  fills  up  the  angle  between 
the  diaphragm  and  the  ribs  ;  the  superior  end  projects  upwards  and 
backwards  along  the  first  rib  and  above  the  level  of  the  clavi- 
cle, so  as  to  be  separated  from  the  scalenus  anticus  muscle  only 
by  the  pleura.  In  laborious  respiration,  the  elevation  of  the 
apex  of  the  lung  is  increased,  and  the  motion  it  produces 
becomes  visible  at  the  root  of  the  neck.  The  external  face  of 
each  lung  is  convex,  to  suit  the  contour  of  the  thoracic  parietes. 
The  internal  surface,  and  especially  that  of  the  left,  is  concave  to 
accommodate  the  heart  and  pericardium.  The  anterior  edge 
is  thin  and  sinuous,  and  presents  on  the  left  side  a  deep  notch 
fitted  to  the  shape  of  the  heart,  and  a  sort  of  lobular  projection 
which  in  part  covers  that  organ  during  deep  inspiration. — 

One  great  branch  of  the  trachea  and  of  the  pulmonary 
artery  passes  from  the  mediastinum  to  each  lung,  and  enters 
it  at  a  place  which  is  rather  nearer  to  the  upper  rib  than  to  the 
diaphragm,  and  much  nearer  to  the  spine  than  the  sternum  : 
at  this  place  also  the  pulmonary  veins  return  from  the  lungs  to 
the  heart. 

These  vessels  are  enclosed  in  a  membrane,  which  is  continued 
over  them  from  the  mediastinum,  and  extended  from  then  to  the 
lung.  Thus  covered  they  constitute  what  has  been  called  the 
Root  of  the  Lung. 

When    their    covering,    derived    from    the    mediastinum,    is 
removed,  the   situation    of  these    vessels    appears   to   be   such 
that  the  bronchia  are  posterior,  the  branches  of  the  pulmonary 
44* 


522  COLOR    OF    THE    LUNGS. 

artery   are  rather  above  and  before,  and  the  veins  below  and 
before  them. 

Each  of  these  vessels  ramifies  before  it  enters  into  the 
substance  of  the  lungs  :  the  bronchia  and  the  branches  of  the 
pulmonary  artery  send  each  a  large  branch  downwards  to  the 
inferior  part  of  the  lungs,  from  which  the  lower  pulmonary 
veins  pass  in  a  direction  nearly  horizontal.  In  general,  each 
of  the  smaller  ramifications  of  the  bronchia  in  the  lungs  is 
attended  by  an  artery  and  a  vein. 

Each  lung  is  divided,  by  very  deep  fissures,  into  portions 
which  are  called  Lobes.  The  right  lung  is  -composed  of  three 
of  these  lobes,  and  the  left  lung  of  two.  (See  fig.  128,  page 
515.) 

— Each  of  these  lobes  are  subdivided  into  many  smaller  parts 
called  lobules,  which  are  marked  out  on  the  surface  of  the  lungs, 
by  various  angular  lines.  The  left  bronchium  divides  into  two 
principal  branches  for  the  lobes  of  the  left  lung,  and  the  right 
into  three  for  the  lung  of  that  side  ;  after  which,  a  still  further 
subdivision  takes  place,  so  that  a  terminal  bronchial  branch  is 
sent  to  each  lobule. — 

The  lungs  are  covered,  as  has  been  already  stated,  with  the 
reflected  portion  of  the  pleura  continued  from  the  mediastinum, 
which  is  very  delicate  and  almost  transparent.  They  have, 
therefore,  a  very  smooth  surface,  which  is  kept  moist  by  exuda- 
tion from  the  arteries  of  the  membrane. 

a*  The  Color  of  the  Lungs  is  different  in  different  subjects. 
In  children  they  are  of  a  light  red  color ;  in  adults  they  are 
often  of  a  light  gray,  owing  to  the  deposition  of  a  black  pig- 
ment in  the  substance  immediately  under  the  membranes 
which  form  their  external  surface.  Their  color  is  often 
formed  by  a  mixture  of  red  and  black.  In  this  case  they  are 
more  loaded  with  blood,  and  the  vessels  of  the  internal  mem- 
branes being  distended  with  it,  the  red  color  is  derived  from 
them. 

The  black  pigment  sometimes  appears  in  round  spots  of  three 
or  four  lines  in  diameter :  under  the  external  membrane  it  is 
often  in  much  smaller  portions,  and  sometimes  is  arranged  in 


STRUCTURE  OF  THE  LUNGS.  523 

lines  in  the  interstices  of  the  lobuli,  to  be  hereafter  mentioned. 
It  is  also  diffused  in  small  quantities  throughout  the  substance 
of  the  lungs. 

The  sources  of  this  substance,  and  the  use  of  it,  are  unknown. 

The  lungs  are  of  a  soft  spongy  texture ;  and,  in  animals  that 
have  breathed,  they  have  always  a  considerable  quantity  of 
air  in  them. 

They  consist  of  cells,  which  communicate  with  the  branches 
of  the  trachea  that  ramify  through  them  in  every  part.  These 
cells  are  extremely  small,  and  the  membranes  which  compose 
them  are  so  thin  and  delicate,  that  if  they  are  all  filled  by  an 
injection  of  wax,  thrown  into  the  trachea,  the  whole  cellular 
part  of  the  lung  will  appear  like  a  mass  of  wax.  If  a  corroded 
preparation  be  made  of  a  lung  injected  in  this  manner  with 
force,  the  wax  will  appear  like  a  concretion. 

These  effects  of  injections  prove  that  the  membranes  of 
which  the  cells  are  formed  are  very  thin  ;  and,  of  course,  that 
their  volume  is  very  small  when  compared  with  the  capacity 
of  the  cells. 

In  those  corroded  preparations,  in  which  the  ramifications  of 
the  bronchia  are  detached  from  the  wax  of  the  cells,  these 
ramifications  become  extremely  small  indeed. — The  cells  above 
alluded  to  are  in  fact  but  the  ultimate  termination  of  the  last 
branches  of  the  bronchia  in  small  dilated  sacs,  called  the  bron- 
chial or  pulmonary  cells. — 

If  the  lungs  of  the  human  subject,  or  of  animals  of  similar 
construction,  be  examined  when  they  are  inflated,  their  cellu- 
lar structure  will  be  very  obvious,  although  their  cells  are  so 
small  that  they  cannot  commonly  be  distinguished  by  the  naked 
eye.  Each  of  the  extreme  ramifications  of  the  bronchia 
appears  to  be  surrounded  by  a  portion  of  this  cellular  sub- 
stance, which  is  gradually  distended  when  air  is  blown  into 
the  ramification. 

This  cellular  substance  is  formed  into  small  portions  of 
various  angular  figures,  which  are  denominated  Lobuli :  these 
can  be  separated  to  a  considerable  extent  from  each  other. 


524  STRUCTURE  OF  THE  LUNGS. 

They  are  covered  by  the  proper  coat  of  the  lungs,  which  is 
extremely  delicate,  and  closely  connected  to  the  general  cover- 
ing derived  from  the  pleurae.  Between  the  lobuli,  where  they 
are  in  contact  with  each  other,  there  is  a  portion  of  common 
cellular  substance,  which  is  easily  distinguished  through  the 
membrane  covering  the  lungs.  This  is  very  distinct  from  the 
cellular  structure  which  coramunicates  with  the  ramifications 
of  the  bronchia,  and  contains  air ;  for  it  has  no  communica- 
tion with  the  air,  unless  the  proper  coat  of  the  lungs  be  rup- 
tured. If  a  pipe  be  introduced  by  a  puncture  of  the  external 
coat  of  the  lungs,  and  this  interstitial  cellular  membrane  be 
inflated,  it  will  compress  the  lobuli.  This  cellular  membrane 
is  always  free  from  adipose  matter :  it  may  be  easily  examined 
in  the  lungs  of  the  bullock. 

Upon  the  membranes  which  compose  the  air-cells,  the  pul- 
monary artery  and  vein  ramify  most  minutely  ;  and  it  seems 
to  have  been  proved  by  the  united  labors  of  chemists  and 
physiologists,  that  the  great  object  of  respiration  is  to  effect  a 
chemical  process  between  the  atmospheric  air,  when  taken  into 
the  air-cells,  and  the  blood  which  circulates  in  these  vessels. 

In  addition  to  the  blood-vessels  which  thus  pass  through  the 
substance  of  the  lungs,  there  are  several  smaller  arteries  deno- 
minated Bronchial,  which  arise  either  from  the  upper  inter- 
costal, or  from  the  aorta  itself;  they  pass  upon  the  bronchia, 
and  are  distributed  to  the  substance  of  the  lungs.  The  veins 
which  correspond  with  these  arteries  terminate  ultimately  in 
the  vena  azygos. 

The  nerves  of  the  lungs  are  small  in  proportion  to  the  bulk 
^  of  these  organs.  They  are  derived  principally  from  the  par 
vagurn  and  the  great  sympathetic  nerves. 

— They  form  one  plexus  on  the  front,  and  another  on  the 
posterior  surface  of  the  bronchia,  along  which  they  are  con- 
ducted to  the  minutest  subdivision  of  the  latter  in  the  substance 
of  the  lungs. — 

The  elasticity  of  the  air-cells  of  the  lungs  and  of  the  ramifi- 
cations of  the  bronchia  which  lead  to  them,  is  apparent  in  their 


STRUCTURE  OF  THE  LUNGS.  525 

rapid  contraction  after  distention,  and  by  the  force  with  which 
they  expel  the  air  which  is  used  to  inflate  them  when  taken  out 
of  the  thorax. 

— The  specific  gravity  of  the  lungs  is  not  naturally  less  than 
that  of  many  other  tissues.  In  a  still-born  child,  sections  of  it 
sink  in  water  like  a  piece  of  muscle.  But  when  its  cells  have 
been  once  distended  by  air  in  respiration  it  becomes  impossible 
to  extrude  the  air  completely  (unless  the  lung  is  subjected  to 
strong  compression)  and  the  lung  floats  upon  the  water  and 
appears  to  have  the  least  specific  gravity  of  all  the  animal  tissues. 
The  lungs  are  endowed  with  a  considerable  degree  of  elasticity ; 
this  as  before  observed  appears  to  be  derived  from  the  elastic 
tissue  of  the  bronchia  which  is  spread  universally  through  the 
lungs.  When  distended  the  lungs  have  a  constant  tendency 
either  in  or  out  of  the  body  to  return  upon  themselves  and 
expel  the  air. 

— It  will  now  be  seen  that  the  proper  tissue  of  the  lungs,  the 
parenchyma,  or  areolar  tissue,  is  very  complicated.  It  consists 
of  the  cells  of  the  bronchia  for  the  reception  of  air,  which  are 
formed  internally  of  mucous  membrane,  and  externally  most 
probably  of  a  thin  expansion  of  the  yellow  elastic  ligamentous 
layer  of  the  bronchia ;  of  branches  of  the  pulmonary  arteries 
and  veins,  which  run  over  the  outer  surface  of  the  cells,  the  for- 
mer bringing  the  black  blood,  and  the  latterconveying  it  away 
after  it  has  been  changed  by  the  action  of  the  air  through  the 
walls  of  the  cells ;  of  the  bronchial  arteries  and  veins  for  the 
purpose  of  nutrition  ;  of  absorbent  vessels  to  remove  the  mole- 
cules as  they  become  effete  ;  of  filaments  of  the  sympathetic  and 
par  vagtim  nerves,  which  preside  over  the  function  of  hematosis, 
and  put  the  lungs  in  connexion  with  the  brain  ;  and  lastly  of 
cellular  tissue  which  unites  the  whole  together.  The  mucous 
membrane  lining  the  trachea,  bronchia,  and  air  cells,  when  ex- 
amined with  the  microscope,  have  been  found  lined  with  a  colum- 
nar epithelium,  mounted  with  vibratile  cilia  of  the  same  kind  as 
has  been  described  covering  the  Schneiderian  membrane.  The 
use  of  the  cilia  in  these  organs,  it  is  believed,  is  that  of  aiding  in 
urging  the  secretions  upwards  towards  the  larynx. 


526  THORAX    OF    THE  FCETUS. 

— Between  the  bronchial  and  pulmonary  arteries  and  veins, 
there  is  an  intimate  anastomosis  so  that  either  system  of  ves- 
sels may  be  filled  by  forcing  a  fine  injecting  fluid  through  the 
other.  The  cells  of  each  lobule,  according  to  Professor  Homer, 
Cloquet,  and  some  other  anatomists  of  distinction,  communi- 
cate laterally  with  each  other.  Reisseissen,  Gerber,  and  other 
microscopists,  figure  each  on§  as  a  perfect  cul  de  sac  ;  the 
development  of  the  lungs  in  the  foetus  resembling  in  its  early 
stages  very  closely  that  of  the  compound  glands.  The  diame- 
ter of  these  cells  has  been  measured  by  Weber  of  Leipzig,* 
by  the  aid  of  a  micrometer  attached  with  extreme  care  and 
ingenuity  to  a  microscope.  According  to  him  they  are  upon  an 
average  about  ^  part  of  an  inch  in  diameter,  which  makes  them 
five  or*  six  times  larger  than  the  cells  of  the  parotid  gland,  and 
fifteen  or  twenty  times  larger  than  the  finest  capillary  blood- 
vessels measured  on  a  portion  of  skin  which  had  been  very 
perfectly  injected  by  Dr.  Pockels  of  Brunswick. — 

The  Thorax  of  the  Fcetus. 

In  the  cavity  between  the  lamina  of  the  mediastinum,  where 
they  approach  each  other  from  the  first  ribs,  is  situated,  a  sub- 
stance which  is  denominated  the 

Thymus  Gland. 

This  substance  gradually  diminishes  after  birth,  so  that 
in  the  adult  it  is  often  not  to  be  found ;  and  when  it  exists  it  is 
changed  in  its  texture,  being  much  firmer,  as  well  as  greatly 
diminished. 

In  the  foetus  it  is  of  a  pale  red  color;  and  during  infancy 
it  has  a  yellowish  tinge.  It  generally  extends  from  the  thyroid 
gland,  or  a  little  below  it,  to  the  pericardium.  From  its  supe- 
rior portion  two  lateral  processes  are  extended  upwards  :  below, 
it  is  formed  into  two  lobes,  which  lie  on  the  pericardium. 

If  an   incision  be   made   into   its   substance,  a   fluid   can   be 


*  Meckel's  Archiv.  fur  Anat.  and  Physiol.,  1830.— 


THORACIC   FASCIA.  527 

pressed  out,  which  has  a  whitish  color,  and  coagulates  upon  the 
addition  of  alcohol. 

Although  it  is  called  a  gland,  no  excretory  duct  has  ever  been 
found  connected  with  it. 

— The  thymus  gland  in  the  foetus  at  birth,  extends  from  the 
fourth  rib,  as  high  up  as  the  thyroid  gland.  It  rests  upon  the 
pericardium  below,  and  is  separated  from  the  arch  of  the  aorta 
and  the  great  vessels,  by  a  fascia,  called  by  Sir  A.  Cooper;  the 
thoracic,  which  is  composed  of  a  dense  layer  of  fibre-cellular 
membrane,  stretched  between  the  concave  margins  of  the  first 
rib  of  each  side  so  as  to  pass  horizontally  across  the  upper  open- 

Fig.  130  * 


ing  of  the  thorax.  It  is  connected  below  with  the  fibrous  sac  of 
the  pericardium,  with  the  arch  of  the  aorta  which  it  in  a  measure 
sustains  and  the  great  vessels  that  come  off  from  it.  Above, 
it  is  connected  with  the  sheath  of  the  carotid,  and  the  deep 
cervical  and  tracheal  fasciae.  This  fascia  has  an  opening  in 

*  A  section  of  the  thymus  gland  at  the  eighth  month,  showing  its  anatomy. 
This  figure  is  taken  from  one  of  Sir  Astley  Cooper's  beautiful  engravings.  1. 
The  cervical  portions  of  the  gland.  The  independence  of  the  two  lateral  glands 
is  well  marked.  2.  Secretory  cells  seen  upon  the  cut  surface  of  the  section ; 
these  are  observed  in  all  parts  of  the  section.  3,  3.  The  pores  or  openings  of 
the  secrelory  cells  and  pouches  ;  they  are  seen  covering  the  whole  internal 
surface  of  the  great  central  cavity  or  reservoir.  The  continuity  of  the  reservoir 
in  the  lower  or  thoracic  portion  of  the  gland,  with  the  cervical  portion,  is  seen, 
in  the  figure. 


528  INTIMATE    STRUCTURE    OF    THE    THYMUS    GLAND. 

front,  through  which  passes  up  the  cervical  portion  of  the 
tbymus  gland. 

— The  gland  consists  of  two  halves,  connected  in  the  middle 
by  cellular  tissue  only,  which  may  properly  be  called  a  right 
and  left  lobe.  According  to  Sir  A.  Cooper,  who  has  published 
a  beautiful  monograph  on  the  structure  of  this  organ,  the 
gland  grows  gradually  with  the  increasing  growth  of  the  foetus, 
till  the  seventh  month.  During  the  ninth  it  is  suddenly  and 
greatly  increased  in  size,  and  at  birth  weighs  two  hundred 
and  forty  grains.  It  continues  to  enlarge  till  the  end  of  the 
first  year  after  birth,  when  it  begins  to  diminish  in  size,  and 
by  the  period  of  puberty  has  almost  entirely  disappeared. 
Each  right  and  left  lobe,  is  composed  of  lobules  disposed  in  a 
spiral  form  round  a  central  cavity,  which  is  called  a  reservoir. 

The  lobules  are  held  together  by  dense  cellular  tissue,  and, 

the  whole  gland  is  surrounded  by  a  coarse  cellular  capsule. 
The  lobules  which  make  this  a  conglomerate  gland  are  very 
numerous,  and  vary  in  size  from  that  of  the  head  of  a  pin  to  a 
common  pea.  In  each  lobule  there  is  a  small  cavity  or  secre- 
tory cell.  Several  of  these  cells  open  into  a  small  pouch,  and 
this  again  into  the  central  cavity  or  reservoir,  which  is  lined  by 
a  vascular  mucous  membrane. 

— Each  lobe  of  the  gland  may  be  carefully  unraveled  by 
removing  the  coarse  cellular  capsule  and  vessels,  and  dissecting 
away  the  firm  cellular  tissue  that  holds  the  lobules  together ; 
the  reservoir  then,  which  in  its  natural  state  is  folded  in  a 
serpentine  manner  upon  itself,  may  be  drawn  out  into  a  length- 
ened tubular  cord,  around  which  the  lobules  are  clustered  in 
a  spiral  manner,  and  resemble  knots  upon  a  cord,  or  a  string 
of  beads.  The  reservoir,  pouches,  and  cells,  contain  a  white 
fluid  like  chyle  or  cream,  with  a  small  admixture  of  red 
globules.  The  use  of  this  gland  is  not  known.  Sir  A.  Cooper, 
is  disposed  to  believe,  in  common  with  several  of  the  older  writers, 
that  the  gland  is  designed  to  prepare  a  fluid  from  the  blood  of 
the  mother,  well  fitted  for  the  growth  and  nourishment  of  the 
foetus  before  its  birth,  and  consequently,  before  chyle  is  formed 
by  it  from  food ;  this  process  continuing  for  a  short  time  after 


THORAX    OF     THE     FOETUS. 


529 


Fig. 


birth — the  quantity  of  fluid  secreted  from  the  thymus,  gradu- 
lly  declining,  as  that  of  chylification  becomes  perfectly  estab- 
shed.—  j 

The  arteries  of  this  body  are  de- 
rived from  the  thyroid  branches  of 
the  subclavians,  from  the  internal 
mammaries,  and  the  vessels  of  the 
pericardium  and  mediastinum. — The 
veins  terminate  mainly  in  the  left 
vena  innominata. 

— The  nerves  are  very  minute,  and 
are  chiefly  from  the  plexus  about  the 
internal  mammary  artery  which  comes 
from  the  superior  thoracic  ganglion  of 
the  sympathetic.  The  lymphatics  ter- 
minate at  the  common  junction  of  the 
other  vessels  of  the  kind,  at  the  union 
of  the  internal  jugular  and  subclavian 
veins.  Sir  A.  Cooper  has  injected 
them  but  once  in  the  human  foetus. 
In  the  calf  he  found  two  large  lym- 
phatic ducts,  see  fig.  131,  which  com- 
mence at  the  upper  extremities  of  the 
lobes,  and  pass  downwards  to  termi- 
nate at  the  junction  of  the  jugular  and 
subclavian  of  each  side.  These  ves- 
sels he  considers  the  absorbent  ducts 

of  the  glands — the   thymic  ducts  which   carry   the  fluid  from 

the  reservoir  of  the  thymus  into  the  veins. — 

The  Heart, 

And  the  great  arteries  which  proceed  from  it,  have  some  very 
interesting  peculiarities  in  the  foetus. 

*  The  course  and  termination  of  the  "  absorbent  ducts  "  of  the  thymus  of 
the  calf;  from  one  of  Sir  Astley  Cooper's  preparations.  1.  The  two  internal 
jugular  veins.  2.  The  superior  vena  cava.  3.  The  thoracic  duct,  dividing  into 
two  branches,  which  re-unite  previously  to  their  termination  in  the  root  of  the 
left  jugular  vein.  4.  The  two  thymic  ducts ;  that  on  the  left  side  opens  into 
the  thoracic  duct,  and  that  on  the  right  into  the  root  of  the  right  jugular  vein. 

45 


530  THE    THORAX    OF     THE    FffiTUS. 

In  the  septum  between  the  two  auricles,  is  a  foramen  of  suf- 
ficient size  to  permit  the  passage  of  a  large  quill,  which  inclines 
to  the  oval  form,  with  its  longest  diameter  vertical  when  the 
body  is  erect.  On  the  left  side  of  the  septum,  a  valve,  formed 
by  the  lining  membranes,  is  connected  to  this  foramen  ;  and 
allows  a  free  passage  to  a  fluid  moving  from  the  right  auricle 
to  the  left ;  but  prevents  the  passage  of  a  fluid  from  the  left  to 
"the  right.  This  structure  is  evidently  calculated  to  allow  some 
of  the  blood  which  flows  into  the  right  auricle  from  the  two 
venae  cavae  to  pass  into  the  left  auricle  of  the  heart,  instead  of 
going  into  the  right  ventricle.  As  the  contents  of  the  left 
auricle  pass  into  the  left  ventricle,  and  from  thence  into  the 
aorta,  it  is  obvious  that  the  blood  which  passes  from  the  right 
auricle  into  the*  left  through  this  foramen,  must  be  transmitted 
from  the  system  of  the  vena  cava  to  the  system  of  the  aorta, 
without  going  through  the  lungs,  as  it  must  necessarily  do  in 
subjects  who  do  not  enjoy  the  foetal  structure. 

— The  valve,  with  which  in  the  foetus  the  foramen  ovale 
is  provided  on  the  side  of  the  left  auricle,  is  of  a  semilunar 
shape  and  called  the  valve  of  Botal ;  it  has  a  convex  border, 
adherent,  and  turned  downwards ;  and  a  concave  border,  free, 
and  turned  upwards.  The  angles  resulting  from  the  union 
of  these  borders  are  at  birth  attached  to  each  side  of  the  fora- 
men about  a  quarter  of  an  inch  distant  from  each  other.  The 
valve  makes  its  appearance  in  the  foetus  at  the  third  month  of 
intra-uterine  existence,  and  gradually  increases  in  size,  so  as 
to  more  than  cover  the  foramen  at  the  period  of  birth.  When 
the  child  breaths  and  the  lungs  become  filled  with  blood,  the 
fluid,  entering  the  left  auricle  by  the  pulmonary  veins,  throws 
down  the  valve  against  the  septum  auriculorum,  to  which  its 
free  border  usually  becomes  firmly  united. 

— Occasionally,  however,  the  union  of  the  parts  is  found  so 
incomplete,  even  in  old  persons,  as  to  allow  a  probe  or  even 
the  handle  of  a  scalpel  to  be  passed  obliquely  through  the 
opening  :  the  obliquity  of  the  orifice  being  such,  as  usually  to 
enable  it  to  act  as  a  perfect  valve.  A  communication  of  this 
sort,  of  greater  or  less  magnitude  between  the  auricles,  exists 


THE    THORAX    OF     THE    FffiTUS.  531 

in  adults,  according  to  Biot,  in  the  ratio  of  one  to  four.  But 
judging  from  my  own  observations,  the  proportion  of  cases  in 
which  the  opening  exists  is  by  no  means  so  great.  Someftimes 
the  foramen  is  met  with  in  adults  so  dilated  as  to  be  nearly  an 
inch  in  diameter.  I  have  met  with  two  cases  of  this  sort  in  the 
dissecting-room,  both  of  which  occurred  in  females  between 
twenty  and  thirty  years  of  age.  The  nutritive  functions 
appeared  to  have  been  perfectly  well  performed  in  both  these 
subjects,  judging  from  the  state  of  the  body  ;  the  right  auricle 
and  ventricle  were  dilated  and  hypertrophied  so  as  to  present 
the  same  thickness  of  parietes  as  the  corresponding  parts  of  the 
left  side.  The  tricuspid  valves,  and  the  semilunar  valves  of  the 
pulmonary  artery  were  thickened,  and  presented  cartilaginous 
concretions  on  their  edges,  in  which  the  work  of  ossification  had 
just  commenced.  This  thickening  and  ossification  of  the  valves 
in  the  normal  formation  of  the  heart  is  almost  wholly  peculiar 
to  the  valves  of  the  left  side,  and  appears  to  be  caused,  as  was 
first  suggested  by  Cruveilhier,  by  the  force  with  which  the  blood 
is  dashed  against  the  valves,  in  the  forcible  contractions  of  the 
ventricle. — 


The,  Pulmonary  Artery  and  the  Aorta, 

Have  a  communication  in  the  foetus,  which  is  very  analogous 
to  the  communication  between  the  auricles  of  the  heart. 

From  the  pulmonary  artery,  where  it  divides  into  the  two 
great  branches,  another  large  branch  continues  in  the  direction 
of  the  main  trunk,  until  it  joins  the  aorta  ;  with  which  vessel  it 
communicates  at  a  small  distance  below  the  origin  of  the  left  sub- 
clavian  artery.  In  the  young  subject  that  has  never  respired, 
it  appears  as  if  the  pulmonary  artery  was  continued  into  the 
aorta,  and  sent  off  in  its  course  a  branch  on  each  side,  much 
smaller  than  itself,  to  each  lung.  In  subjects  that  have  lived 
a  few  days,  these  branches  to  the  lungs  are  much  larger ;  and 
then  the  main  pulmonary  artery  appears  to  have  divided  into 
three  branches  :  one  to  each  lung,  and  one  to  the  aorta ;  but 
that  which  continues  to  the  aorta  is  larger  than  either  of  the  others. 


532  GENERAL    OBSERVATIONS. 

In  the  course  of  time,  however,  this  branch  of  the  aorta  is 
contracted,  so  that  no  fluid  passes  through  it ;  and  it  has 
the  appearance  of  a  ligament,  in  which  state  it  remains. 

The  course  of  the  blood  from  the  right  ventricle,  through  the 
pulmonary  artery  to  the  aorta  below  its  curve,  is  more  direct 
than  that  from  the  left  ventricle  to  the  same  spot  through  the 
aorta  at  its  commencement.  The  column  of  blood  in  the  aorta 
below  its  curve  is  evidently  propelled  by  the  force  of  both 
ventricles :  and  this  circumstance,  although  it  seems  to  pro- 
ceed merely  from  the  state  of  the  foetal  lungs,  is  particularly 
calculated  for  the  very  extensive  circulation  which  the  foetus 
carries  on,  by  means  of  the  umbilical  arteries  and  vein  in  the 
placenta. 

The  Lungs  of  the  Fwtus 

Differ  greatly  from  those  of  the  adult.  They  appear  solid, 
as  if  they  were  composed  of  the  parenchymatous  substance 
which  constitutes  the  matter  of  glands,  rather  than  the  light  spongy 
substance  of  the  lungs  of  adults.  They  differ  also  in  color  from 
the  lungs  of  older  subjects,  being  of  a  dull  red. 

They  have  greater  specific  gravity  than  water ;  but  if  air  be 
once  inspired,  so  much  of  it  remains  in  them  that  they  ever 
afterwards  float  in  the  former  fluid. 

The  nature  of  the  process  of  respiration,  and  its  effects  upon  the  animal 
economy,  particularly  upon  the  action  of  the  heart,  appear  to  be  much  better 
understood  at  this  time  than  they  were  before  the  discovery  of  the  composition 
of  the  atmosphere,  by  Dr.  Priestley  and  Mr.  Scheele.  The  publications  upon 
this  subject,  which  have  appeared  since  that  period,  namely,  1774,  are  there- 
fore much  more  interesting  to  the  student  of  medicine  than  those  which 
preceded  them.  Two  of  these  publications  ought  to  be  particularly  noticed 
by  him ;  namely,  an  essay,  by  Dr.  Edward  Goodwyn,  entitled,  "  The  Con- 
nexion of  Life  with  Respiration  ;  " — and  the  "  Physiological  Researches  of 
M.  Bichat  upon  Life  and  Death."  Part  Second.* 

The  general  doctrines  respecting  the  oxygenation  or  decarbonization  of  the  blood 
and  the  absolute  necessity  that  it  should  take  place  to  a  certain  degree  in 

*  The  student  will  derive  much  information  respecting  the  publications  on  this  subject, 
prior  to  1804,  from  Dr.  Bostock's  Essay  on  Respiration.— Since  the  publication  of  that  essay 
several  interesting  papers  on  respiration  have  appeared,  namely,  Two  Memoirs  by  the  late 
Abbe  Spallanzani ;  "  An  Inquiry  into  the  Changes  induced  on  Atmospheric  Air  by  the  Ger- 
mination of  seeds,"  &c.,  by  Ellis  ;  two  very  important  communications  by  Messrs.  Allen  and 
Pepys  in  the  Transactions  of  the  Royal  Society  of  London  for  1808  and  1809  ;  and  "  Farther 
Inquiries  into  the  Changes  induced  on  Atmospheric  Air,"  also  by  Ellis. 


CASES  OF    MALFORMATION.  533 

order  to  preserve  life,  are  confirmed  by  a  number  of  cases  of  malformation 
of  the  heart  or  the  great  vessels,  in  which  the  structure  was  such  that  a  con- 
siderable portion  of  venous  blood  passed  from  the  right  side  of  the  heart  to 
the  aorta,  without  going  through  the  lungs.  In  these  different  cas^s,  not- 
withstanding the  structure  was  somewhat  varied,  the  symptoms  produced 
were  very  much  alike  j  differing  in  the  respective  patients  in  degree  only, 
and  not  in  kind. 

The  symptoms  indicating  this  structure,  are  blue  color  of  the  face,  (such  as 
generally  accompanies  suffocation,)  extending  more  or  less  over  the  whole 
body,  and  particularly  apparent  under  the  nails  of  the  fingers  and  toes ; 
anxiety  about  the  region  of  the  heart ;  palpitation ;  laborious  respiration ; 
sensations  of  great  debility,  (fee. :  all  of  which  are  greatly  aggravated  by 
muscular  exertion.  These  effects  have  generally  appeared  to  be  proportioned 
to  the  quantity  of  venous  blood  admitted  into  the  aortic  system.* 

When  these  appearances  take  place  immediately  after  birth,  it  is  probable  that 
they  depend  entirely  upon  malformation  of  the  heart  or  great  vessels  ;  but 
when  they  commence  at  a  subsequent  period,  they  are  commonly  the  effect  of 
a  diseased  alteration  in  the  lungs.  They  sometimes  occur  near  the  termina- 
tion of  fatal  cases  of  pneumonia  or  catarrh  ;  but  a  different  cause,  which  has 
not  latterly  been  suspected,  appears  to  have  produced  them  in  the  following 
case,  related  by  Dr.  Marcet,  in  the  first  volume  of  the  Edinburgh  Medical 
and  Physical  Journal. 

The  blue  color  occurred  in  a  young  woman,  twenty-one  years  of  age,  in  whom 
it  had  never  been  observed  before.  It  came  on  during  an  affection  of  the 
breast,  and  was  attended  with  great  prostration  of  strength  and  difficulty  of 
breathing,  as  well  as  cough,  oedema  of  the  hands  and  feet,  and  several  other 
symptoms.  About  seven  weeks  after  the  commencement  of  these  symptoms, 
she  died ;  when  it  was  ascertained  by  dissection,  that  there  was  no  unnatural 
communication  whatever  between  the  cavities  of  the  heart,  and  that  its  valves  were 
all  in  a  perfect  and  natural  state.  The  lungs  were  free  from  tubercles,  or  any 
other  appearance  of  disease.  Their  substance  seemed  more  compact  than 
usual,  especially  the  left  lung,  although  it  did  not  sink  in  water;  but  they 
adhered  every  where  to  the  inner  surface  of  the  thorax,  to  the  diaphragm  and  to 
the  pleura  covering  the  pericardium.  This  case  is  the  more  remarkable,  be- 
cause numberless  instances  have  occurred,  in  which  very  large  portions  of 
the  external  surface  of  the  lungs  have  been  found,  upon  dissection,  to  adhere 
to  the  internal  surface  of  the  thorax,  without  the  occurrence  of  such  symp- 
toms during  life. 

It  may  be  inferred,  from  a  statement  published  by  M.  Dupuytren,  in  a  volume 
of  the  Proceedings  of  the  National  Institute  of  France,  that  the  oxygenation 
or  decarbonation  of  the  blood  is  much  affected,  in  respiration,  by  an  influence 
exercised  by  the  nerves  which  are  appropriated  to  the  lungs.  From  his 
account  it  appears,  that  although  the  complete  division  of  the  eighth  pair  of 
nerves  produces  death  after  some  time  ;  yet  in  the  horse,  whose  nerves  are 

*  Cases  of  this  kind  are  related  in  several  of  the  periodical  publications  on  medical  sub- 
jects. Two  of  them  were  described  by  Dr.  William  Hunter  in  the  sixth  volume  of  "  Medical 
Observations  and  Inquiries  by  a  society  of  Physicians  in  London ; "  one  quoted  by  Dr. 
Goodwyn,  is  in  the  Observationes  Anatomicae  of  Sandifort ;  and  another  by  Dr.  J.  8. 
Dorsey,  has  been  published  in  the  first  number  of  the  New  England  Journal  of  Medicine  and 
Surgery. 

45* 


534       EFFECT  OF  VENOUS  BLOOD  ON  THE  HEART. 

thus  divided,  life  continues,  and  respiration  goes  on,  from  half  an  hour  to 
ten  hours ;  but  his  arterial  blood  is  in  a  state  of  great  disoxygenation  or 
carbonation  during  this  time.  This  fact  is  more  remarkable  because  venous 
blood,  contained  in  a  bladder  exposed  to  the  open  air  will  become  oxygenated 
or  decarbonated. 

It  is  also  asserted  in  another  Memoir,  read  to  the  National  Institute  by  Dr.  J.  M. 
Provencal ;  that  animals,  in  whom  the  eighth  pair  of  nerves  has  been  divided, 
do  not  consume  so  much  oxygen,  or  produce  so  much  carbonic  acid,  by  a 
considerable  degree,  as  they  did  before  the  division  of  these  nerves ;  and  that 
their  temperature  is  considerably  reduced.* 

The  effect,  that  venous  blood  occasions  death,  when  it  is  admitted  into  the  left 
ventricle  of  the  heart,  and  the  aorta,  is  truly  important.  Dr.  Goodwin 
explained  it  by  suggesting  that  this  blood  was  not  sufficiently  stimulating  to 
produce  the  necessary  excitement  of  the  heart ;  but  on  this  occasion  one  of  his 
friends  proposed  to  him  the  following  question  :  Why  does  venous  blood  affect 
the  left  side  of  the  heart  in  this  injurious  manner,  when  it  appears  to  exert  no 
noxious  effects  whatever  on  the  right  side  of  that  organ  ?  His  reply  may  be 
seen  in  a  note  at  the  82d  page  of  his  Essay,  in  the  first  edition.  Bichat  has 
offered  a  solution  which  completely  resolves  this  difficulty,  viz.  "  The  effect  of 
venous  blood  upon  the  heart  is  produced  by  the  presence  of  this  blood  in  the 
proper,  or  coronary  arteries  of  that  organ,  and  not  in  its  great  cavities."  For 
the  animation  of  the  heart,  like  that  of  the  other  parts  of  the  body,  depends 
upon  the  state  of  the  blood  in  the  arteries  which  penetrate  its  texture.f  And 
•while  the  heart  acts,  the  blood  of  the  coronary  arteries  will  be  the  same  with 
that  of  the  left  ventricle.  See  Bichat's  Researches,  P.  II.  art.  6,  $  2. 

The  French  anatomists  at  one  time  entertained  some  peculiar  opinions  respecting 
the  course  of  the  blood  in  the  fostus,  which  have  a  particular  relation  to  the 
subject  last  mentioned.  Winslow,  who  paid  great  attention  to  the  valve  of 
Eustachius  in  the  right  auricle  of  the  heart,  was  of  opinion,  that  this  valve 
was  calculated  for  some  important  purpose  in  the  foetal  economy.!  Although 
his  hypothesis  respecting  its  particular  use  has  not  been  retained  by  his 
countrymen,  many  of  them  have  adopted  his  general  sentiment ;  and  among 
others  Sabatier.  That  learned  anatomist  believed  that  this  valve,  in  the 
foetal  state,  serves  to  direct  the  blood  of  the  inferior  cava,  after  its  arrival  in  the 
right  auricle  through  the  foramen  ovale  into  the  left  auricle  ;  while  the  blood  of 
the  upper  cava  passes  directly  into  the  right  ventricle.  His  opinion  seems  to  be 
supported  to  a  certain  degree — 

1.  By  the  direction  in  which  the  two  columns  of  blood  enter  the  auricles 
from  the  two  venae  cavae. 

2.  By  the  position  of  the  Eustachian  valve. 

3.  By  the  foraman  ovale,  when  its  valve  is  complete ;    as  the  passage 
through  it  from  the  right  to  the  left,  is  at  that  time  oblique,  and  from  below 
upwards. 

*  These  Memoirs  were  republished  in  the  Electic  Repertory  of  Philadelphia  for  April  and 
October,  1811. 

t  It  is  probable  that  the  contents  of  the  great  cavities  of  the  heart  have  no  more  effect 
upon  its  animation  than  the  contents  of  the  stomach  and  bowels  have  upon  the  animation 
of  those  organs. 

J  See  Memoirs  of  the  Academy  of  Sciences  for  1717  and  1725, 


SENTIMENTS  OF  SABATIER,  ETC.  535 

The  theory  of  Sabatier  appears  to  be  this  :— the  umbilical  vein  brings  from  the 
placenta  blood  which  has  a  quality  essential  to  the  animation  of  the  foetus. 
If  there  were  no  particular  provision  to  the  contrary,  a  large  portion  of  this 
blood,  after  passing  from  the  umbilical  vein  by  the  inferior  cava  into^rhe  right 
auricle  of  the  heart,  would  proceed  by  the  right  ventricle  through  the  pulmo- 
nary artery  and  arterial  canal,  into  the  aorta,  below  the  origins  of  the  carotid 
and  subclavian  arteries ;  and  consequently  none  of  it  would  pass  to  the  head 
and  upper  extremities,  but  a  considerable  part  would  return  again  by  the 
umbilical  arteries  to  the  placenta,  without  circulating  through  the  body  :  while, 
on  the  other  hand,  the  blood  which  passed  by  .the  carotid  and  subclavian 
arteries  to  the  head  and  upper  extremities  returning  from  them  to  the  heart 
by  the  superior  cava,  might  pass  from  the  right  auricle  to  the  left  auricle  and 
ventricle  and  the  aorta,  and  so  to  the  head  and  upper  extremities  again, 
without  passing  through  the  placenta.  But  by  means  of  this  valve,  the  blood 
of  the  lower  cava,  and  of  course  of  the  umbilical  vein,  is  directed  to  the  left 
auricle  and  ventricle  and  the  aorta,  by  which  a  considerable  portion  of  it  will 
necessarily  pass  to  the  head  and  upper  extremities  ;  while  the  blood  which 
returns  from  these  parts  by  the  superior  cava,  must  consequently  pass  from 
the  right  auricle  into  the  right  ventricle  and  pulmonary  artery;  from  whence 
a  large  portion  of  it  will  proceed  through  the  arterial  canal  into  the  aorta 
beyond  the  carotids  and  subclavians,  and  of  this  portion  a  considerable  part 
will  go  to  the  placenta  by  the  umbilical  arteries.  Sabatier  'compares  the 
course  of  the  blood  in  the  foetus  to  the  course  of  a  fluid  in  a  tube  which  has 
the  form  of  the  numeral  character  8.*  If  this  doctrine  be  true,  the  progress 
of  the  blood  in  the  fostus  and  placenta  is  very  analagous  to  that  of  the  double 
circulation  of  the  adult ;  the  character  8  answering  equally  well  in  the 
description  of  either  subject. 

According  to  Sabatier,  the  blood  of  the  placenta  takes  this  peculiar  course 
through  the  heart,  in  order  that  some  of  it  may  be  carried  to  the  head  and 
upper  extremities.  But  an  additional  reason  may  be  suggested,  which  appears 
to  be  of  great  importance  ;  namely,  the  supplying  of  the  coronary  or  proper 
vessels  of  the  heart,  with  some  of  the  same  blood. 

The  heart  of  the  adult,  as  has  been  before  stated,  cannot  act  without  its  proper 
or  coronary  arteries  are  supplied  with  arterial  blood.  The  heart  of  the  foetus 
performs  a  more  extensive  circulation  than  that  of  the  adult,  and,  therefore, 
is  probably  in  greater  need  of  such  blood.  But  unless  the  blood  of  the  placenta 
pass  through  the  foramen  ovale  into  the  left  auricle  and  ventricle,  and  so  to  the 
aorta,  it  cannot  enter  the  coronary  arteries  which  originate  at  the  commencement  of 
the  aorta  ;  for  the  blood  which  flows  from  the  right  side  of  the  heart  through 
the  arterial  canal,  passes  into  the  aorta  at  so  great  a  distance  from  the  orifices 
of  the  coronary  arteries,  that  it  certainly  cannot  enter  them. 

The  whole  of  this  doctrine  seems  to  be  supported  by  a  fact  very  familiar  to 
accoucheurs,  viz.  the  occurrence  of  death  in  the  foetus  whenever  the  circula- 
tion through  the  umbilical  cord  is  suspended  during  fifteen  or  twenty  min- 
utes ;  for  as  the  placenta  imparts  to  the  foetal  blood  a  quality  essential  to 
life,  some  arrangement  seems  necessary  to  provide  for  the  equal  distribution 

*  See  Sabatier's  Paper  on  this  subject,  in  the  Memoirs  of  the  Academy  of  Sciences,  for 
1774. 


536  ^         USUAL  CASES   OF  MALFORMATION. 

of  the  blood  which  comes  from  this  organ,  and  especially  for  carrying  the 
requisite  proportion  of  it  to  the  substance  of  the  heart. 

Life  has  existed  for  some  time  with  a  structure  very  different  indeed  from  that 
which  is  natural.  In  the  series  of  elegant  engravings  relating  to  morbid 
anatomy,  published  by  Dr.  Baillie,  is  the  representation  of  a  heart,  in  which 
the  venae  cavae  opened  into  the  right  auricle,  and  the  pulmonary  veins  into 
the  left  auricle,  in  the  usual  manner ;  but  the  aorta  arose  entirely  from  the 
right  ventricle,  and  the  pulmonary  artery  as  completely  from  the  left.  The 
canalis  arteriosus,  however,  passed  from  the  pulmonary  artery  to  the  aorta, 
and  the  foramen  ovale  existed.  In  this  case,  it  is  evident,  that  the  pulmonary 
artery  must  have  carried  back  to  the  lungs  the  arterial  blood  which  came 
from  them  by  the  pulmonary  veins,  with  a  small  quantity  of  venous  blood 
that  passed  into  the  left  auricle  through  the  foramen  ovale;  and  that  the  aorta 
must  have  returned  to  the  body  the  venous  blood,  which  just  before  had  been 
brought  from  it  by  the  venae  cavae,  with  a  small  addition  of  arterial  blood 
that  passed  through  the  ductus  arteriosus.  Yet  with  this  structure  the  child 
lived  two  months  after  its  birth. 

A  case,  which  had  a  strong  resemblance  to  the  foregoing,  occurred  in  Philadel- 
phia, and  was  examined  by  the  author  of  this  work.  The  venae  cavae  termi- 
nated regularly  in  the  right  auricle,  and  the  pulmonary  veins  in  the  same 
regular  manner  in  the  left ;  but  the  pulmonary  artery  arose  from  the  left 
ventricle,  and  the  aorta  from  the  right.  There  was  no  communication  between 
these  vessels  by  a  canalis  arteriosus  ;  but  a  large  opening  existed  in  the  septum 
between  the  auricles. 

It  is  very  evident,  that,  in  this  case  also  the  pulmonary  artery  must  have 
returned  to  the  lungs  the  arterial  blood  as  it  came  from  them,  and  the  aorta 
must  have  carried  back  to  the  general  system  the  venous  blood  brought  to 
the  heart  by  the  cavae  j  excepting  only  those  portions  of  the  arterial  and 
venous  blood  which  must  have  flowed  reciprocally  from  one  auricle  into  the 
other,  and  thus  changed  their  respective  situations. 

The  subject  was  about  two  years  and  a  half  old.  The  heart  was  nearly  double 
the  natural  size,  and  the  foramen,  or  opening  in  the  septum  between  the 
auricles,  was  eight  or  nine  lines  in  diameter.  The  pulmonary  artery  was 
larger  in  proportion  than  the  aorta  or  the  heart. 

With  this  organization,  the  child  lived  to  the  age  above  specified.  His 
countenance  was  generally  rather  livid ;  and  this  color  was  always  much 
increased  by  the  least  irregularity  of  respiration.  His  nails  were  always 
livid.  He  sometimes  appeared  placid,  but  more  frequently  in  distress.  He 
never  walked,  and  seldom,  if  ever,  stood  on  his  feet.  When  sitting  on  the 
floor,  he  would  sometimes  push  himself  about  the  room;  but  this  muscular 
exertion  always  greatly  affected  his  respiration.  He  attained  the  size 
common  to  children  of  his  age,  and  had  generally  a  great  appetite.  For 
some  weeks  before  death  his  legs  and  feet  were  swelled. 

It  is  probable  that  the  protraction  of  life  depended  upon  the  mixture  of  the 
blood  in  the  two  auricles ;  and  that  they  really  were  to  be  considered  as  one 
cavity,  in  this  case. 

There  seems  reason  to  believe,  that  in  adults  of  the  common  structure,  there  is 
no  passage  of  blood  from  one  auricle  to  the  other,  when  the  foramen  ovale 


FORAMEN  OVALE.  537 

has  remained  open ;  because  in  several  persons  in  whom  it  was  found  by 
dissection  to  have  remained  open,  there  were  no  appearances  during  life, 
that  indicated  the  presence  of  disoxygenaied  blood  in  the  aortic  system.  It 
is  probable,  that  the  small  size  of  the  foramen  ovale,  the  valvular  structure 
which  generally  exists  there,  and  the  complete  occupation  of  the  left  auricle 
by  the  blood  flowing  from  the  pulmonary  veins,  prevent  the  passage  of  blood 
from  the  right  auricle  to  the  left,  in  such  persons ;  whereas  in  the  case  in 
question,  the  opening  between  the  auricles  was  very  large  indeed,  and  there 
was  no  appearance  of  a  valve  about  it. 

Although  it  be  admitted,  that  in  adults  with  the  foramen  ovale  pervious,  there 
is  no  transmission  of  blood  from  the  right  to  the  left  auricle  ;  there  is  every 
reason  to  believe,  that  this  transmission  goes  on  steadily  in  the  foetus.  To 
the  arguments  derived  from  the  structure  and  the  nature  of  the  case,  it  may 
be  added,  that  the  pulmonary  veins,  in  the  foetal  state,  carry  to  the  left  auri- 
cle a  quantity  of  blood,  not  sufficient  to  fill  it ;  while  the  vense  cavae  carry  to 
the  right  auricle,  not  only  the  whole  blood  of  the  body,  but  of  the  umbilical 
cord  and  placenta :  some  of  which  must  flow  into  the  unfilled  left  auricle, 
when  the  right  auricle  becomes  fully  distended. 

The  question,  how  far  the  functions  of  the  heart  and  lungs  are  dependent  upon 
the  brain,  is  very  important,  and  has  often  been  agitated  with  great  zeal.  In 
favor  of  the  opinion  that  the  motions  of  the  heart  are  independent  of  the 
brain,  may  be  stated  the  numerous  cases  in  which  the  brain  has  been  deficient 
in  children,  who  have  notwithstanding  lived  the  full  period  of  utero-gesta- 
tion,  and  even  a  short  time  after  birth,  and  have  arrived  at  their  full  size, 
with  every  appearance  of  perfect  vigor  and  action  in  the  heart.  In  support 
of  the  doctrine,  that  the  action  of  the  heart  is  immediately  dependent  upon 
the  brain,  it  may  be  observed,  that  no  organ  of  the  body  appears  to  be  so 
much  influenced  by  passions  and  other  mental  affections  as  the  heart.  These 
contradictory  facts  have  occasioned  this  question  to  be  considered  as  unde- 
cided, if  not  incapable  of  solution  ;  although  Cruikshank  and  Bichat*  have 
stated  circumstances  very  favorable  to  the  opinion  that  the  motions  of  the 
heart  are  independent  of  the  brain. 


This  question  seems  now  to  be  settled  by  the  experiments  of  Dr.  Legallois,  a 
physician  of  Paris,  which  prove,  that  in  animals  who  have  suffered  decapi- 
tation, the  action  of  the  heart  does  not  cease  as  an  immediate  consequence 
of  the  removal  of  the  head  ;  but  its  cessation  is  an  indirect  effect,  induced  by 
suspension  of  respiration.  That  respiration  is  immediately  affected  by 
decapitation,  and  depends  upon  the  influence  of  the  brain  transmitted 
through  the  eighth  pair  of  nerves.  That  the  action  of  the  heart  will  con- 
tinue a  long  time  after  decapitation,  if  inflation  of  the  lungs,  or  artificial 
respiration,  be  performed;  but,  on  the  contrary,  if  the  spinal  marrow  be  de- 
stroyed, the  action  of  the  heart  ceases  irrecoverably. 

The  inference  from  these  experiments  seems  very  conclusive,  that  the  Spinal 
marrow,  and  not  the  brain,  is  the  source  of  the  motions  of  the  heart. 

*  See  Cruikshank's  Experiments  on  the  Nerves  and  Spinal  marrow  of  living  Animals ; 
London  Philosophical  Transactions  for  1795.  The  eighth  experiment  has  a  particular  relation 
to  this  subject.  Bichat's  researches,  part  2,  article  9. 

The  Abbe  Fontana  has  considered  this  subject  in  his  Treatise  on  the  Venom  of  the  Viper, 
vol.  ii.  page  194,  English  translation  ;  and  also  in  some  of  his  other  works. 


538  HUMBOLDT  AND  OTHERS  ON    LEGALLOls'  PAPER. 

It  appears  also  by  some  of  the  experiments,  that  the  power  of  motion  in  the 
trunk  of  the  body,  is  derived  from  the  spinal  marrow  ;  and  that,  when  this 
organ  is  partially  destroyed,  the  parts  which  receive  nerves  from  the  destroy- 
ed portion  soon  cease  to  live.  By  particular  management  of  the  spinal 
marrow,  one  part  of  the  body  can  be  preserved  alive  for  some  time  after  the 
other  parts  are  dead. 

These  experiments  of  Dr.  Legallois,  commenced  in  1806,  or  1807,  were  com- 
municated to  the  imperial  Institute  of  France,  in  1811.  The  committee  of 
that  body,  to  whom  they  were  referred,  namely,  Messrs.  Humboldt,  Halle, 
and  Percy,  reported  that  the  experiments  had  been  repeated  before  them,  at 
three  different  meetings  of  several  hours  each  ;  and  that,  to  allow  themselves 
sufficient  time  for  reflection,  they  suffered  an  interval  of  a  week  to  take  place 
between  the  meetings.  The  committee  believe  these  experiments  to  have 
proved, 

1st.  That  the  principle  upon  which  all  the  movements  of  inspiration  depend, 
has  its  seat  about  that  part  of  the  medulla  oblongata  from  which  the  nerves 
of  the  eighth  pair  arise. 

2nd.  That  the  principle  which  animates  each  part  of  the  trunk  of  the  body, 
is  seated  in  that  portion  of  the  spinal  marrow  from  which  the  nerves  of 
the  part  arise. 

3d.  That  the  source  of  the  life  and  strength  of  the  heart  is  also  in  the  spinal 
marrow  ;  not  in  any  distinct  portion,  but  in  the  whole  of  it. 

4th.  That  the  great  sympathetic  nerve  is  to  be  considered  as  originating  in 
the  spinal  marrow,  and  that  the  particular  character  of  this  nerve  is  to  place 
each  of  the  parts  to  which  it  is  distributed  under  the  immediate  influence  of 
the  whole  nervous  power. 

The  interesting  memoir  of  Dr.  Legallois  is  confirmed  to  a  certain  degree  by  a 
communication  of  B.  C.  Brodie  to  the  Royal  Society  of  London  in  1810,  in 
which  are  detailed  many  very  interesting  experiments,  which  induced  the 
author  to  conclude, 

That  the  influence  of  the  brain  is  not  directly  necessary  to  the  action  of  the 
heart ;  and 

That  when  the  brain  is  injured  or  removed,  the  action  of  the  heart  ceases 
only  because  respiration  is  under  its  influence;  and  if,  under  these  circum- 
stances, respiration  is  artificially  produced,  the  circulation  will  still  continue. 
These  various  experiments  apply  particularly  to  the  cases  in  which  the  brain  is 
deficient,  the  effects  of  mental  agitation  on  the  heart  are  likewise  reconcila- 
ble to  the  theory  which  arises  out  of  them.  But  they  throw  no  light  on  the 
question  why  the  motions  of  the  heart  are  so  perfectly  free  from  the  influence 
of  the  will :  and  although  they  seem  to  prove  incostestably  that  the  motion 
of  the  heart  is  independent  of  the  brain,  it  ought  to  be  remembered  that  in 
certain  diseased  states  of  the  brain,  where  that  organ  appears  to  be  com- 
pressed, the  action  of  the  heart  is  often  very  irregular,  and  its  contractions 
less  frequent  than  usual. 

— For  a  later  and  more  accurate  account  of  the  functions  of  respiration,  the 
reader  is  referred  to  Dunglison's  "  Human  Physiology,  6th  Ed.,  Phila. 
1846.— 


END    OF    VOL.    I. 


